Entitled "PSP Go Rewards", the process involves registering your new PSP Go to the Playstation Store, then logging into the Playstation Store with an existing PSP and a UMD in the drive. You'll get a PSP Go theme for your troubles and a voucher (via email) for use with the PSP Go.
The voucher will gain you free access to 17 full PSP titles, including Killzone: Liberation, SOCOM: US Navy SEALs Fireteam Bravo 3, WipEout Pure, Everybody's Golf, echochrome, Buzz!: Brain Bender, Buzz!: Master Quiz, LocoRoco and Patapon.
PSP Go Rewards will run from October 1st right the way up to March 31, 2010.
It's not going to please those with large UMD collections, but then it's not like Sony's going to come and take your existing PSP and UMDs off you when you upgrade. Quite the contrary. Three free games is a very nice offer for those looking to upgrade for sure. Don't forget you'll also get Gran Turismo PSP with the PSP Go.