Today Adobe announced Creative Suite 5.5. If you'll recall, CS 5 was announced April 12, 2010 and began shipping on April 30, 2010. Adobe has indicated that their intent is to ship a new version of the Creative Suite every 2 years, with a mid-cycle "dot release" to address current technology changes and trends.
Bottom line: The update contains Acrobat X, changes to InDesign, InCopy, Flash Catalyst, Flash Professional, Dreamweaver, After Effects, Audition, Device Central, and Media Encoder, as well as a new (optional) subscription pricing model, and integration of the Adobe Digital Publishing Suite. Note specifically that this update doesn't add any new features to Illustrator or Photoshop.