The only validity to the pool hopping exploit I can see is if you could put yourself in a position where you started off at Bitcoin Pooled Mining (BPM) and had a decent chunk into it and bailed toward the end for Bitcoin Pool (BP). From what I have read, and I could be wrong or outdated info, shares at BPM are weighted more heavily toward the end so if you had a decent stake in the current block at BPM and managed to switch over to BP at the beginning of a new block to establish a stake there too. Both blocks would have to terminate rather quickly and at about the same time for it to work and not have the shares get ate up at BPM.

It's possible, but highly unlikely considering you would have to get lucky with the timing on both sites.