I just took a survey today for Sony as recommended PSP user. The bulk of the survey dealt with a "unnamed PSP rental service". The survey broke down into several categories for content in different proposed "memberships" which included:
Subscription period: Plans ranged from weekly, monthly, quarterly, semi annually, and annually.
Monthly fee: after locking in on a period, monthly fees ranged from $5 a month to $15. (Total yearly cost never exceeded 49.99 for a year plan)
Number of rentals a month: This ranged from 1 to unlimited rentals a month.
Number of new games released a month: This ranged from a disappointing 0 to as high as 20+ a month.
Availability for rental: This ranged from "Day of release" (implying it would be available to rent same day the game could be bought either in store or online) to "12 months after release"

    Though the survey didn't have actual fixed numbers, it did imply 3 types of memberships. It followed the trend of:
1.) A yearly membership (usually around $40-$50 for the year) that allowed unlimited downloads but games tended to be at least one month after release.
2.) A 3 month or 6 month membership (monthly fees averaging $10-12) these would have a limited number of rentals, usually 5-10, but most games would be recent, ranging from day of release to 3 months after release.
3.) A monthly membership (though usually the cheapest, if you had it for a year it was the most expensive, much live xbox live gold being cheaper to buy a year and a month) This membership offered a very limited number of downloads, usually topping out at 5 a month and didn't recieve newer games and possibly no new releases in that month.

     The survey also clearly stated that you would have to go online with your psp to authenticate your games every time your membership renewed. It also claimed that a massive update to the number of titles was on the way.  It also implied retail copies of PSP games would still be available in UMD form (unlike what Patapon 2 did).

    The survey closed with several questions about storage space and the importance of "gaming on the go". Nothing was mentioned about a hard drive, but there was a lot of inphasis on the lack of storage on the PSP.

    This survey dealt only with the PSP and there was no mention of the PS3 or charging for Playstation Network.

    Nothing was set in stone, but seeing as the main focus of the survey was this "unnamed PSP rental service" I would expect to hear about this service along side the reveal of the new PSP (currently known as PSP Go!) at Sony's press conference at E3.