Debian wheezy: GCC 4.5.2, Berkeley DB 5.1, GMP 5.0.1
Here's just a short notice that GCC/G++ 4.5.2 is now the default compiler in Wheezy. To test it, I've just recompiled the kernel (Linus' 2.6.37), and it's working great. Berkeley DB libdb-dev now depends on libdb5.1-dev instead of libdb4.8-dev. And finally, GMP (GNU multiprecision arithmetic library) is up to 5.0.1.
All those upgrades have broken numerous development libraries, so if you're into heavy development, watch out! The list of development libraries I'd like to have installed, but are broken right now includes: libsvn-dev, libaprutil1-dev, libserf-0-0-dev, apache2-prefork-dev, libmpc-dev, libmpfr-dev, libcloog-ppl-dev, librasqal3-dev, librdf0-dev, libslv2-dev and nettle-dev. But, in some cases you can force some of those, but only if you sacrifice some other stuff.
Other than that, Wheezy is in pretty good shape. Iceweasel 4 beta 12 has been running great, I enjoy playing YouTube videos with HTML5 instead of flash.