As far as I know, GCC and Clang have the most complete C++11 implementations, and I use many C++11 features daily in GCC 4.7.2. (Planning to give Clang another whirl, but haven't gotten around to it yet.)
But neither fully supports it yet, just as GCC doesn't. Even when they claim to support every feature in the standard, that's just the beginning -- next comes fixing all the bugs and corner cases that naturally arise from a spec as complex as C++11.
And? Essentially the same thing happened with C++98, and in the long run it didn't hurt adoption too much. To me, it seems like the compiler are doing a better job this time around.
The point is that it's silly to criticize GCC for having incomplete C++11 support one year after the standard has finalized, and even sillier to point to other compilers' less-complete support as evidence that GCC is falling behind.
Last time I checked C++11 has been an ISO standard since last August, with MS and Clang ramping up their support for it.