For those of you unsure whether or not to upgrade to 5.03 I suggest you stay on version 4.01.
The Gripshift exploit has been patched by version 5.03 meaning if you upgrade to that to try this proof of concept your placing all your eggs in one basket , Matiaz did promise some awesomness in the next few days but i'm not a gambling man , 2 potential exploits on my PSP sounds a whole lot better than 1.
of course if this exploit results in some kind of kmode access then all the above will be irrelevant.