Update:
Us Weekly confirms that Ashlee Simpson is engaged, and she may even be pregnant:

A rep for Simpson tells Us, "Yes, they are happily engaged."

Earlier today, the singer told Us, "I'm really happy!"

One possible cause for the quickie engagement - a pregnancy, to which her rep had no comment and referred Us to friendsorenemies.com, where Simpson posted the following Wednesday:

"We know there has been a lot of speculation recently about Pete and I, and we wanted our fans to be the first to know, because you guys are the best. Yes, we are thrilled to share that we are happily engaged."

People, meanwhile, reports Ashlee is engaged, but forgot (since corrected) how to spell her name (Ashlee not Ashley). See screengrabs:

Previously:
Ashlee Simpson is engaged to singer Pete Wentz, according to In Touch:

In Touch can exclusively reveal that Ashlee Simpson is engaged to boyfriend Pete Wentz! "He got down on one knee and she said yes," a family friend tells In Touch. The couple went away to Colorado just days ago where Pete's brother had an art exhibit, and that is where Pete, 28, popped the question to Ashlee, 23. "She has an amazing ring, and they are so in love," adds the friend. And Ashlee's parents, Joe and Tina, not only approve but are thrilled! The couple that started dating in October 2006, have not set a date for the wedding just yet. Congrats Pete and Ashlee!

Simpson is also well known as the lip synching "Saturday Night Live" guest, as the younger sister of singer and divorcee Jessica Simpson and for her very public nose job.