Sorry to bump this ass-ancient thread, but these forums serve largely as a repertoire of information for people searching, and I don't want someone who searches to wind up walking away from this with the wrong impression. Also Kazade is totally still around here.
We now have BOTH atomics AND std::future working fine with the latest toolchain with the latest version of KOS. The atomics were partially implemented by the compiler and partially by me. The way you can implement them is by disabling interrupts, doing the "atomic operation" then enabling interrupts afterwards. If the scheduler can't preempt the thread, and no interrupts can occur... it's "atomic!" We have them for both C11 and C++11.
Then secondly, yes, std::future works fine now. As does std::async.