Which compilers (as of May 2014) are able to generate code that uses the transactional memory capabilities (Restricted Transactional Memory, not simply lock elision)?
GCC, as of version 4.8 supports Intel RTM:
Support for the Intel RTM and HLE intrinsics, built-in functions and code generation is available via -mrtm and -mhle.
It's probably safe to assume that similar intrinsics are available for a recent version of Intel's ICC, however I can't find a particular version that specifies support (this paper did experimentation with RTM) .
In addition, support likely exists for various smaller languages and JITs, with more transparent support arriving sometime in the future.