Yesterday it was announced that Adobe will be announcing (gotta love announcements announcing announcements) Creative Suite 4 on September 23rd.
Adobe will be holding a special little event online showing all of the upcoming features of CS4 (which is rumored to be released as early as this Fall).
For those hip to trying out beta products, you can already checkout CS4 versions of Dreamweaver, Fireworks, and Soundbooth. Though, be warned, downloading and installing these could cause some conflicts should you need to re-install any CS3 software (I know it gave me some issues).
The current version of Creative Suite (CS3) was released on April 20, 2007.