UPDATE:
PSP GO Announced
1. 16gb on board flash memory
2. 3.8 inch screen
3. 43% lighter than the PSP 3000
4. Blue Tooth Support
5. All Digital Content No UMD
6. You can add extra memory via memory card slot
7. Games , Movies , TV Shows, To Go
8. Releases This Fall 2009
Also the PSP GO! Will not be alone; along side it will come Gran Turismo GO!, Jak & Daxter, and the Infamous Metal Gear Solid.
http://www.eurogamer.net/gallery.php?article_id=587698#anchor