Sony's Director of PlayStation Network Operations Eric Lempel has announced the following today:
Hi, everyone, I wanted to give you a quick heads up that a new PSP firmware update, v5.03, will be released soon. This is a small update that improves system software stability during use of some features.
Although he didn't specify it, as expected the PSP update also patches the user mode exploit hole found in GripShift recently.
That being said, do not update if you have a TA-088 v3 motherboard on your PSP-2000 Slim or if you have a PSP-3000 and wish to run homebrew code. Sony has now added a check that automatically detects the savedata as corrupt, and will refuse to display it on the list of available saves.