Is where any C++ compiler that supports C++0x features already?
GCC has some of it supported. See here.
Both the 2008 Visual C++ 'Feature Pack' and g++ support some features.
The list of C++0x features supported by g++.
The Visual C++ 2008 Feature Pack ... includes an implementation of TR1. Portions of TR1 are scheduled for adoption in the upcoming C++0x standard as the first major addition to the ISO 2003 standard C++ library. Our implementation includes a number of important features such as:
Microsoft's Visual Studio 2010 CTP (Community Technology Preview) contains support for four C++0x features namely lambdas, auto, static_assert, and rvalue references.
You can download the VPC image here, make sure to read the bit about accounting for the January 1 2009 expiry date (this blog post is referenced).
Scott Meyers has a nice detailed summary of C++0x support across some common compilers here:
http://www.aristeia.com/C++0x/C++0xFeatureAvailability.htm
There are compilers that partially support C++0x, but there can't be full support yet because the final C++0x has not yet been standardized.