I'm in that same position. I was logging in less and less and finally decided I wasn't playing enough for it to be worth the $15 a month so I decided to quit for a while. I haven't played for about a month now. I plan on coming back eventually, maybe with patch 4.1 and the new dungeons, but I just got bored. It's weird, because I haven't lost interest in the game itself -- I still read WoW Insider every day, I keep up with the most recent patch notes, I get on the forums every so often -- but the current content just hasn't grabbed me like previous expansions.

I also have the same feeling. I am seriously struggling to find motivation to log on now. The only reason I would (as I havent been able to force myself for the last 3 weeks) is for the friends I have made in the game.
My alts I made - are neglected, as even though the new 1-60 content is good, thats not why I play the game.
My 85's (and one 83), I dont want to log, as I just cant force myself to PUG a heroic again, and whilst my main is always welcomed into raids, I just feel underperforming or just plain incompetent now. (as an example the last time I raided, most of the team were working on their 4th part T11 or better - after the raid I got my 1st piece - usually Im one of the best dps - now im struggling to beat the tank at times) And I dont want to slow up my guildies.
I am welcomed by my guild, but I no longer feel I want to be there. The next time I log I will probably dish out my gold and mats to various people and quit tbh :(. Tis sad as I came into the game in TBC and loved it ever since, but cata seems lacking somehow. Maybe it is the very linear questing, which I cannot face again after doing two times (and this with my main being loremaster etc etc), or the raiding, which I cannot seem to get excited about in any way. Either way I think im gonna be taking a long break, possibly forever and thats very sad.
Too much grinding, not enough fun for me anymore. GL everyone with it, Im sure it will get better.