NEW YORK (AP) — Apple says Mac users downloaded 3 million copies of Mountain Lion, its latest operating system, in the first four days it was available.

That makes it the fastest launch of an Apple operating system ever, the company says. It released Mountain Lion Wednesday.

Apple charges $20 for the software. That pays for downloads for all of a buyer's personal computers.

Apple also provides the OS for free to buyers who bought a Mac on or after June 11.

Mountain Lion brings features from the iPhone and iPad to the Mac. The enhancements include tight integration with Apple's online storage service, iCloud, and a "Notification Center" that shows incoming mail, calendar reminders and other events.

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Check out the gallery (below) to see some awesome Mountain Lion features that you might not ever use.
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  • Dictation

    With Dictation, you can "talk anywhere you can type," <a href="http://www.apple.com/osx/whats-new/" target="_hplink">as Apple puts it</a>. That's apt: Wherever you see a cursor, you can double-tap the "fn" button and the familiar Siri Microphone animation pops up. Dictation works quickly -- words pop up on your screen soon after you finish speaking them -- and the software even understands commands like "ALL CAPS" and requests for punctuation marks like "comma," "period," and "question mark" (which is great until you have to write a term paper about grammar). As a reporter, I'm keen to try Dictation to automatically transcribe interviews I've recorded. Otherwise, I can't see myself talking to my computer, either at work or at home. I use Dictation on my iPhone constantly, especially when I'm texting on the move. I'm never working on my MacBook Pro while walking or driving, however, so it seems a tad less useful, in practice, to me.

  • AirPlay Mirroring

    Owners of <a href="http://www.cultofmac.com/178460/the-real-reason-why-macs-before-2011-cant-use-airplay-mirroring-in-mountain-lion-feature/" target="_hplink">newer Macs with the correct hardware</a> can wirelessly mirror their monitors to a television screen through an Apple TV box, meaning that all those movies and shows you've been watching on your computer can now be sent straight to your big screen, in up to 1080p high-definition. I don't own an Apple TV so I'm afraid I'm out of the loop on this one -- for Apple TV owners, however, AirPlay Mirroring could justify the $20 upgrade alone.

  • Notification Center

    One of many design elements lifted from iOS, the Notification Center can be accessed by swiping two fingers to the left on your touchpad. The vertical bar houses notifications from all of your apps, including by default Calendar, FaceTime, Game Center, Mail, Messages, Reminders, Safari. You can customize your Notification Center from the System Preferences menu, and if you sign in to Twitter, you can even send a Tweet straight from the Notification Center itself. I don't really use Calendar, FaceTime, Game Center, Mail, Messages, Reminders, or Safari, so I'm still awaiting my first notification. Hope it's a memorable one!

  • Messages

    The Messages app has replaced iChat as the pre-installed chat client for Mac. Its hallmark feature allows you to send and receive iMessages, those free, blue-colored messages that you get on your iPhone when talking to other friends with iPhones. With that feature, you no longer have to pick up your phone in order to text iPhone-wielding friends; that can be accomplished straight from the desktop, and you can access all of your iPhone's old iMessages on your Mac, too. I'm still using Adium, a third-party chat client, as well as in-browser Gchat, for my messaging purposes. Is iMessaging from the desktop reason enough to switch? I'm not convinced yet -- I'm generally never far from my iPhone -- but could be swayed: The idea of accessing past iMessages and conversations anywhere is tempting.

  • Documents In The Cloud

    With an iCloud account on Mountain Lion, you can now sync your documents in the cloud so that whenever you make changes to files on Documents, Numbers, or Keynote, those changes show up automatically on other computers and devices. If this sounds like what Google Docs has been doing for about five years -- well, it is just about what Google Docs has been doing, through a web browser, for about five years; with the introduction of Google Drive and offline document editing, it's another tough sell to get me to switch. I already have so many documents and files saved with Google Docs, from years and years of usage, that transferring everything over to Apple's system seems like a hassle. I'd also rather my documents be operating system-agnostic, so that I can easily access them from a Windows machine or Android phone if I need to.

  • Sharing Buttons

    The Share Button appears on several of Apple's desktop apps, including Mail, Messages, and Safari, and lets you share a webpage, photo, or video to Twitter or Facebook with a couple clicks. As I said in the intro, while sharing buttons on the iPhone (and Android) are huge time-savers, I find that they have less utility on a desktop, where multi-tasking and switching between apps and tabs and windows is so, so much easier and faster on the larger screen. The advantages of actually seeing what you're sharing to a social network -- rather than blindly sending it off from a drop-down menu -- make me wonder what the Share Button on the desktop is good for in most cases.

  • Offline Reading List

    One neat feature on the new Safari (which, full disclosure, I don't use and don't plan on switching over to) is the Offline Reading List, which allows surfers to save the text of webpages for later reading, even without an Internet connection. It's a neat trick, albeit one that Apple "borrowed" from popular apps like Instapaper and Pocket (formerly Read It Later). I've had the "Add To Read It Later" button bookmarked on my Chrome browser for a couple years now, and it's a great service. Those who browse with Safari and aren't already using Instapaper, Pocket or a similar app might enjoy getting started with Apple's excellently convenient (though not totally original) Offline Reading List.

  • Game Center

    Never used it and never will, though I suppose if you're an iOS gamer and/or a fan of fake felt this could be big news.

  • Twitter And Facebook Integration

    You can now log into your Twitter account within Mountain Lion (just as you can in iOS 5 on the iPhone or iPad); soon, you'll be able to do the same with Facebook. That will supposedly make it easier to share things to your profile or tweet about whatever it is you're looking at on your desktop; again, however, given how much easier it is to multitask on a desktop or laptop than on a smartphone or iPad, this function seems superfluous to me. If you had the option of being able to see exactly what you were posting, and that option took perhaps two seconds more time than using a Share button, wouldn't you give up your two seconds and just visit Twitter or Facebook to get the full experience?