Richard Guenther announced GCC 4.7 RC1 shortly after branching the 4.7 release series and then opening up trunk to GCC 4.8 development. The brief release announcement can be found on the GCC mailing list. Richard is hoping to release GCC 4.7 final in the next three weeks.
In terms of hardware improvements for GCC 4.7, there's noticeable work on the AMD x86 support, better support for Intel Sandy Bridge and Ivy Bridge CPUs (AVX, rdrand / Bull Mountain, etc), initial Intel Haswell CPU support (AVX2, FMA, BMI1, BMI2, etc), and various work on the ARM SoCs for the ARMv7 architecture such as the ARM Cortex-A7.
On the language side, there's better support for Google Go, more feature support for C11, better C++11 support, improved libstdc++ support for C++11, and much more. There's also version 3.1 of the OpenMP specification for C, C++, and Fortran compilers. The C++11 (C++0x) support is still considered experimental within GCC.
Some other highlights for GCC 4.7 include initial support for transactional memory in C, link-time optimization (LTO) improvements, several new compiler options, inter-procedural optimization improvements, and more.