I just did it, minus the hot glue and using a piece of clear plastic the same shape as the back of the d-pad plastic piece itself (rather than the NES-shaped d-pad 'cross' suggested on the page). The whole thing took about 5 minutes. The difference was immediate and massive. Anyone who has had their PSP for more than 90 days has nothing to lose by doing this (your warranty has already expired) and
everything to gain. Very, very cool. Hopefully Sony will see this and fix it themselves in the next hardware revision.