In a way, I guess they've been available since the DiMarzio SDS came out in '79, but theres a few out there now:
Fralin steel pole
Rio Grande Dirty Harry
BG Strat P90
Vintage vibe single coil P90
DiMarzio SDS
I think about these from time to time. Anyone tried one?
Generally I find a normal BK strat pickup with a base plate is chunky enough for my bridge position, but I can't help wondering if the grass is greener ;)