PSP Go Rewards
SCEE has blessed us European PSP Go early adopters that have a bunch of UMD’s lying around with a scheme called “Rewards”, which will allow you to convert 3 of your favourite UMD’s to digital format for the UMD-less Go model.
No, this won’t be a huge benefit to anyone with 40 UMD’s lying around, movies and games, but it certainly helps out a lot in the migration to know you can get your copy of Killzone Liberation on the new machine.
It also seems most of the titles (if not all) are based on first party Sony published titles, including Buzz, Patapon & Echochrome.
The instructions to get going are as follows:
1. Unwrap your shiny new PSPgo and start it up
2. Connect to PlayStation®Network and activate your new or existing PlayStation Network account for PSPgo Rewards
3. Start up your current PSP and connect to PlayStation Network
4. Login using the same PlayStation Network account , and launch PlayStation®Store
5. Pop one of your UMDs into the drive of your current PSP and register on PSPgo Rewards when prompted
6. Download a PSPgo theme
7. Wait for your email voucher for your three free games
8. Choose, download and enjoy!
The promotion coincides with the launch of the device on October 1st (Thursday). Stay tuned for more!

I had read the deal was that as long as you have 1 UMD you could download any 3 of the listed games, doesn't matter if your UMD isn't one of those.
So in that sense its a good deal but I certainly see no reason to upgrade.
Hopefully a future update firmware will allow UMD conversion, if the hackers managed it then surely Sony can.