If you want to buy things from Sony, you're going to have to be patient for a little while longer.
Sony says that despite any rumors you have might heard to the contrary, the PSN store will not be coming back online today or tomorrow. Sony debunked the rumors on a post on the PlayStation blog, where it announced eight hours of "routine maintenance" at the same time.
The source of the rumors was a memo supposedly sent to Sony's development partners. The memo said that Sony planned to restore the store today, and then push updates twice a week for the next two weeks in order to catch up on the missed content. The memo said that if developers had concerns about timing, then Sony was willing to be flexible with what came out when.
Some developers have voiced concerns about the restoration of the PSN store, although the complaints have been more about games being lost in the deluge of content, or overlooked in favor of the free games that Sony is offering as an apology for the problems with PSN.
Sony has not announced a firm timetable for the restoration of the PSN store, only saying that it was aiming to have the store back in action by the end of the month. That could mean anytime between now and May 31, presuming that Sony is able to get things working by then.
Source: PlayStation Blog