Now that Sony has confirmed it will (and is going to ask third parties to) provide digital (and apparently retail physical) versions of PSP UMDs, that means that when you switch on a PSP2, you should already have loads of games to play.
Assuming you only have to enter in your PSN id, then I've got a whole bunch of games linked to my digital account. We just have to hope there is a smart upscaling routine to make full use of the screen's improved resolution.
The only thorn will be if you have to pay to convert a UMD into a digital copy. Ideally, there should be a PSP app that reads your disc, gives you a code which you enter into your PSP2 for a free digital copy, then *somehow* registers or borks the UMD so that it can't be used again.
If they want to do it the hard way, how about offering free trade-ins at stores? Even if its something like buy a PSP2 game, get two PSP games converted for free - it'd help owners keep their beloved collections intact. That could also be used to flog off those last few PSP Go units (hey - I'd buy one if it was under £100, just as a backup for my ancient Mk.1 Japanese PSP)
Even if that isn't possible, there is little value in old UMDs, so losing a few sales due to duped codes won't kill the developers now concentrating on ultra-secure, *cough*, unhackable PSP2 games.
Of course, those pesky licensing and rights issues could create a lot of issues, as they have with PSOne games for the PSN store. Also, I have some Japanese and U.S. UMDs, bet they wouldn't work.