Interestingly, Dan Savage ("Savage Love") has a column dealing with this subject this week. Evidently it's even gotten the nickname "pegging" (as in strapping on).
http://www.thestranger.com/seattle/SavageLove
I've an admitted bias in being gay, but I've always said if guys could lose the preconceptions that having something stuck up their ass to massage their prostate is "homosexual" a lot more of them would find out about it and enjoy the sensation.