Sony will be changing user accounts on the day most likely to make everyone think it's an elaborate prank. Joystiq reports that on April 1, your Sony Computer Entertainment (SCEA) account, including the funds in your wallet, will be transferred to Sony Network Entertainment America (SNEA).
The new arm of the company will be handling online services from now on, so you'll need to agree to a new Terms of Service and User Agreement. You can opt out, in which case SNEA will return any existing funds in your account and, presumably, cut you off from the PlayStation Network. The new ToS agreement can be viewed at Qriocity, implying that Sony is making good on its promises to tie the music and movie service more directly to the PlayStation brand.
The network change comes as Sony prepares to roll out the NGP. Sony seems to be positioning the device to compete with the runaway success of the iPhone, so bringing all of the network activities under one umbrella would be a sensible move in that direction. Even if, you know, it involves Qriocity.