They surveyed 1,000 gamers (which is not a huge sample, actually), and found that almost half had actually met another player in real life, and one in ten developed "physical relationships" with someone they'd met in a game. 40% of people discussed sensitive issues with online friends rather than real-life ones, and 30% of players were attracted to another player. 80% of players also played not only with online friends, but with real-life friends and family as well. And according to the study, women were more likely to both be attracted to other players, and to eventually date them, and while women play for "therapeutic refreshment," men play for "curiosity, astonishment, and interest."
50% of respondents said World of Warcraft was their game of choice, so while the study was actually about MMO players, it's not a stretch to say it's just about WoW players (and pretty hardcore players, too-- average play time per week was 22.85 hours!). Like I said, 1,000 people is a pretty small sample, but apparently a journal approved it-- the study will be published in CyberPsychology and Behavior.