It looks like Sony is removing the ability access the PlayStation store via the PSP from next week, at least according to this post on a German site. The confusion is though whether this means Sony is just removing store access, or whether closing down all PSN services for the handheld. Apparently this change will come from the server side of operations, not a firmware update, so there will be no way to gain accessibility.
After the Playstation Portable has recently received a firmware update to version 6.60 3 years ago, and they just left was allowed to lie since that was announced today that the PlayStation Store will be removed access via the PSP from the September 15, 2014.
That change will take place on the server side, and not via a firmware update, so neither modified firmware, not-updating will not help.
PSP titles will still be transferred via a computer with or without Media Go on your PSP device, as it always has been and to give input on the E1000. The function new content to download via Wifi but omitted from approx next week. Especially for owners of a PSP Go this is a slap in the face, because those depend on the PSN store, if they (the remainder strongly recommended) firmware does not have piped unofficial.
The PS Vita is not affected by this change, fortunately, if one uses the pre-installed PSN Store App of the PS Vita.
According to the sent email, however, you should still be able to view the download list on the PSP, from a wireless download option, as it is possible to date / was, there is unfortunately nothing.
This means that PSP owners will no longer be able to purchase games through the store, but apparently will have access to the download list so you can still acquire your older games. Though the vast majority of PSPs use UMDs you can still buy games for them that way. However PSPGo owners are right out of luck if they wish to buy any new games for the console.
We’ve contacted Sony to clarify whether this affects just the store, or if this means all services, including multiplayer, will be shut off.