C++ 0x is the next version of C++ with some added language features, libraries etc. The C++ standard committee is planning to have it released around the end of the decade. The "0x" is because the year of release is unknown.
The GCC 4.3+ compiler has support for some of the C++ 0x features, also some of the features was released as part of TR1 in MS Visual C++.Net 2008. I will blog about TR1 and C++ 0x features in the future.