Over at Science Blogs, Coturnix offers a picture and description of Pseudobiceros hancockanus flatworms, which have both male and female organs.
Which one gets to be which in any given encounter is decided by “penis fencing.” Natural selection, proving its endless ability to be politically incorrect, has decreed that the winner gets to be the guy.
“The one who is inseminated has to bear and lay eggs--a more expensive proposition," Coturnix writes. "The one who ‘won’ the fencing bout and did the insemination can move on and fence some other guys and on and on, ‘fathering’ many progeny until happening onto a better fencer, getting inseminated, and spending the rest of the life as ‘mother.’"
(FYI the picture, also found in Wikipedia, is entirely safe for work--that is, unless your cubicle neighbors are invertebrates.)
For a brief moment I tried to contemplate how this might work out in the bars on Saturday night. Then I washed my brain out with soap, went back to the computer, and presently came upon a Wired story about sex in video gaming.
OMG. Of course. Before August rolls around, surely some geek with too much spare time will create a multiplayer game in which everybody can have a hermaphroditic flatworm avatar, with the lifestyle and everything.