There is an interview up about all the changes that have occurred for season 7, some highlights in the spoilers. My words so hopefully it's ok because I wasn't sure if I could post the link or not.
Click to see Spoiler:-weekly partner switching
-no choosing genres (instead the contestants will draw a photo out of a hat that represents the style)
-no top 20 (straight out of Vegas at top 10)
-partners will come from a "pool" of past contestants and choreographer assistants called "all-stars"
-only one person eliminated each week.
-AND Mia Michaels is back....
There is more, Nigel issued a press release today about all the changes.