Sounds promising. That may be the tipping factor to getting me to get one. I Like titles on the Nintendo DS but hate the ergonomics (or lack thereof) but being able to try PSP ones withought paying full price would be very nice.
If the price is right, this would be big for titles that are only worth it for single player/story/campaign mode. Or maybe they could make this into a try before you buy thing, wherein if you want to buy the game you could (discounted the rental price).
I'm skeptical. While it would be great to try before I buy, companies aren't thinking about that these days. Companies, not realizing that demand drives prices, can't understand why people don't pay more for the same product they are already getting. I mean, movie companies seem to think $1 per viewing is too little for a movie (this Redbox is evil). $1 per song is too little (thus iTunes is evil). And $15/month for as many moves you can move through the mail 3 at a time is too little (thus Netflix is evil). Not only that, but not getting more money when a product that's already been paid for is resold is really bad (thus Gamestop, Thrift-stores, used book stores, etc.. are true evil)
No, expiration won't be for the purpose of giving more to the consumer. Rather, they'll probably use it to turn off games they don't want you playing anymore (why play Madden 2009? Madden 2010 is already out!!!).
I hope they do bring rentals to psp then the homebrew community will figure out a way for unlimited rental time or free rentals, so i don't have to download and hook my psp to my pc. i find that a real hassle.