After Apple unveiled iOS 6 at the Worldwide Developers Conference on Monday, many iPhone and iPad owners were certainly drooling over the attractive new features soon to come to their devices. Turn-by-turn directions in Maps! FaceTime video calls over 3G! The ability to save webpages for offline reading!

Well, here comes some potentially bad news: If you have an older model iPhone, iPad, or iPod Touch, not all of the new features announced on Monday will be available to download when iOS 6 is released in the fall.

Here's the breakdown, as posted in the footnotes of the iOS explainer site on Apple.com:

- Siri will no longer be exclusive to the iPhone 4S; it will also make the leap to the iPad 3. This means that the Siri functionality in the new Maps -- the ability to ask for directions, or attractions along your route -- will only be available on those two devices.
- The iPhone 3GS and iPhone 4 will not receive turn-by-turn directions or the "Flyover" 3D mapping feature (per MacWorld).
- The "Shared Photo Stream" feature, which allows iDevice users to share photos with other iDevice users and comment on each other's pictures, will only be available for the iPhone 4 or later, the iPad 2 or later, and Mac computers with OS X Mountain Lion.
- FaceTime over 3G will require an iPhone 4S or iPad 3 with cellular data capability. No 3G FaceTime for anything older than those two gadget.
- VIP list -- which allows users to mark certain email addresses as important, so that new emails from those accounts pop up like text messages -- is only available on the iPhone 4 or later and the iPad 2 or later. Ditto for VIP and Flagged mailboxes, separate inboxes for more important emails in the Mail app.
- Offline Reading List -- an Instapaper-like feature that allows for saving of webpage content for reading when you don't have an Internet connection -- will only be available on the iPhone 4 or later and the iPad 2 or later.
- In general, iOS 6 will be available only for the iPhone 3GS and later, the iPad 2 and later, and the fourth-generation iPod Touch.

...and that's that.

Now, some of these non-updates come with explanations. Apple seems to think that its top-of-the-line A5 processor, for example, is necessary to sufficiently power video chats over 3G. Why Siri cannot run on the iPad 2 or iPhone 4, however, remains a mystery to some critics, and Apple has stayed typically mum. The inability of the iPhone 3GS and first-generation iPad to run seemingly simple utilities like the Offline Reading List and VIP mailboxes may breed more suspicion, doubt, and mystery surrounding Apple's motives.

Whatever those motives are, the key takeaway is that Apple has again chosen to keep some of its most impressive features, announced with much fanfare and hype at a slickly-produced event, exclusive to its newest hardware. You can read all about those features in our iOS 6 wrap-up here, and check out a comprehensive run-down of everything that Apple announced here.

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  • New iOS 6

  • "Do Not Disturb" For Phone App

  • Screening Calls In iOS 6

  • Facebook Integration

  • No More Google Maps

  • Apple Turn By Turn Directions

  • More Of The New Map App

  • Scott Forstall Talks iOS 6