The main product page lists the major new features in Production Premium. Studio Daily has an nice overview of the suite, plus a new video on the Warp Stabilizer for editors, by AE product manager Steve Forde.
Reviews on the updated Premiere include Review: Adobe CS5.5 Production Premium by Shawn Lam and Adobe Premiere Pro hits 5.5 by Scott Simmons.
Adobe evangelist Jason Levine has more on his blog, Production Premium CS5.5 – Getting Better All The Time, with an overview of new features in the video suite. Here’s his video overview; Adobe TV has the rest in the CS 5.5 feature tour.