I don't think you can argue that the external HDD for the original PS2 is proof of Sony's error. When FFXI came out, external HDD's were available and you could play the games you were supposed to be able to play.
The PSX is different. It's a veritable fiasco and it's interesting to note how little press this story is getting. There's no excuse for promising certain features and then backing out -- what you have is not buyer's remorse with "next year's model" being better, it's false advertising. Sony screwed up.
Now, being a first-gen buyer of the PSP likely won't have the same effect. Instead, it'll be more like GBA versus GBA-SP in my opinion. A 1st gen PSP must still be able to run all UMD videos and games in the future. What'll likely happen is that PSP rev2 will have better battery life. So as an early adopter, you'll likely put up w/bad battery life -- but I don't think you'll see the same thing as the PSX.
That said, Sony has done full refund buybacks before. They did it with the eMarker and eVilla.
http://news.com.com/2100-1040-272675.html?legacy=cnet
http://news.com.com/2100-1040-272399.html?legacy=cnet
Interestingly both of these products were supposed to be "convergence" type products...