Since joining the forum, I would say I've moved a smidgen to the left on economic issues, and was more of a left-libertarian in the past. Perhaps most notably, I support universal healthcare now. I haven't really changed that much, though. I think my PM score has moved quite a bit, but then again changing my answer on museums hardly represents a real political change IMO. I've always been perplexed by the frequent (and rapid!) changes some folks on this forum have.
This also applies to me perfectly, albeit these changes were a couple years or so before I joined the forum.