[Note: The header image is over Matthew "Gaymer" Brown as seen on Sony's The Tester, not the trademark guy going after Reddit. Sorry if I didn't make that clear enough.]
Although "Gaymer" has entered our cultural vernacular (even a convention's using it), the term is trademarked to a single man, Chris Vizzini. He started the Gaymer.org website in 2007, and is now exercising his right to the word -- sending a cease-and-desist to Reddit.
Vizzini wants the /r/gaymers community to change its name or otherwise face legal action. Reddit users are concerned that their community might effectively be shut down, while Vizzini argues that he has to pursue this or otherwise risk losing his trademark altogether. He doesn't want the community to be banned, he's hoping to just have it renamed.
Unfortunately, trademarks can only be upheld if their owners are willing to challenge any and all infringement, regardless of how unpopular it makes them. Still, others argue that the word should never have been trademarked anyway, since it's such a common portmanteau that gamers have commonly used for years.
Gaymer.org is currently down. It's not yet known if it's a result of this issue.
Everyone's hoping for an amicable solution. Still, it's amazing what words people own these days. I never thought anybody had a "right" to a term used on message boards, at events, and on television (as per our header image). With the amount of people and products that have used it, I have to wonder how successfully the trademark's been upheld over the years.