A commenter in the open Sunday thread complained about WoW and video game burnout, sitting in front of his computer and "just don't feel like playing". Well, the good news is that you are not alone. Especially World of Warcraft is definitely in a burnout phase, where lots of players have played through all or most of the new content of Wrath of the Lich King, and are bored or waiting for the next content patch.
Personally I'm a bit burned out as well with World of Warcraft, so I reduced the time I spend in the game. Curiously in my guild there has been a series of players quitting the guild, for reasons I can only assume are also related to burnout. I say curiously, because while several of these players cited the reason that our guild isn't hardcore enough, and want to join a more hardcore guild, our guild in fact finished Naxx 25, and is now working on Malygos. It isn't as if a more hardcore guild would have access to content our more casual guild isn't already doing. In fact it is likely that a more hardcore guild is having a far easier time than we do in Naxx 25, which is if anything *more* boring than playing with a guild which still needs to focus at the harder encounters. So while the train of thought "I'm bored" -> "Can't possibly be my fault" -> "Let's blame the guild and /gquit" is a classic one, I don't really see how joining a more hardcore guild is going to help right now. We're all in the same boat, waiting for Ulduar.
World of Warcraft or Wrath of the Lich King is like a book. A strange book, in which you don't have to read all chapters in order. But sooner or later you do have read all chapters, and your only options are to read the same chapters again and again, or to wait for the sequel. Burnout is completely natural, and there isn't anything negative about it. The negative thing is how some people handle it.
Switching to a different game doesn't always help, especially not if the new game isn't all that different. If you are burned out from WoW, playing another MMORPG in which you have NPCs with floating symbols over their head asking you to go out and kill 10 foozles might not help much. Or if you play one first-person shooter a lot, switching to a different one isn't going to bring back the fun for long. Sometimes switching the genre completely does help, especially if you go out and play various smaller games instead of concentrating on one big game.
But if you don't feel like playing, I can only advise you to not play. There is more to life than video games. Besides spending more time with friends and family, there are also lots of other entertainment options: books, magazines, TV, movies, DVD, surfing the internet, etc.
The important thing to realize is that burnout is something that is happening with *you*. No, it isn't World of Warcraft that suddenly changed to be less fun. No, your guild mates and online friends aren't to blame. It's you who is changing, who is getting bored, who is burning out. So try to handle it in a mature manner, without burning down bridges in a fit of rage. Explain to your guild mates that you will play less, or take a break. Unsubscribe if you really want to take a prolonged break, but don't delete your characters or give all your stuff away, there is a big chance you'll want to come back one day. If you are lucky enough to be in a good guild, with nice people, you'll still be welcome after your break, because the others in your guild cherish you as a person, and not just because of your character stats and raid performance. I'm very happy to be in a guild like that, and we had lots of burned out people recently coming back and be welcomed. Real people tend to last a lot longer than games and avatars.