That's what I read too. It seems that her and Colin's (Auggie) characters will leave the show.

Yes, it is true that Ashlee has been fired from the show. The same goes for Colin (Auggie). According to what I read their characters will no longer be of use to the show when the whole murder story arc is completed. I think they will still be in episodes until January, then new characters will be introduced to the show.

Here's the article I found on this: www.popeater.com/2009/10/22/ashlee-simpson-wentz-fired...ce/