GCC version 4.5.1 Pre-Release SVN rev. 161239, 2010.06.23  (Status: 2010-04-18) ();
mingw runtime version 3.18.20100623; w32api version 3.14.20100623; gmp-4.3.2; mpfr-3.0.0; ppl-0.10.2; cloog-ppl-0.15.9; libelf-0.8.13; Binutils 2.20.51.20100623; zlib-1.2.5; mpc-0.8.2; mingw-w64 (svn rev.2588 20100622), pthreads 2.9.0.0 (static).

GCC 4.5.1, with corrections for any critical defects reported in GCC 4.5.0, is expected in July, 2010.

GCC configured with:

$ gcc -v
Using built-in specs.
COLLECT_GCC=e:\mingw_msys\msys.450x64v2\mingw\bin\gcc.exe
COLLECT_LTO_WRAPPER=e:/mingw_msys/msys.450x64v2/mingw/bin/../libexec/gcc/i686-pc-mingw32/4.5.1/lto-wrapper.exe
Target: i686-pc-mingw32
Configured with: ../src/configure --prefix=/mingw_new --build=i686-pc-mingw32 --target=i686-pc-mingw32 --with-sysroot=/mingw_new --with-build-sysroot=/mingw_new --with-libelf=/mingw_new/build_libs --with-mpfr=/mingw_new/build_libs --with-gmp=/mingw_new/build_libs --with-ppl=/mingw_new/build_libs --with-cloog=/mingw_new/build_libs --with-mpc=/mingw_new/build_libs --with-host-libstdcxx='-lstdc++ -lsupc++ -lm' --with-system-zlib --enable-static --enable-threads=win32 --enable-languages=c,c++,fortran,objc,obj-c++ --enable-version-specific-runtime-libs --enable-multilib --enable-lto --disable-debug --disable-rpath --disable-shared --disable-win32-registry --disable-bootstrap --disable-nls
Thread model: win32
gcc version 4.5.1 20100623 (prerelease) (GCC)

$ x86_64-w64-mingw32-gcc -v
Using built-in specs.
COLLECT_GCC=e:\mingw_msys\msys.450x64v2\mingw\bin\x86_64-w64-mingw32-gcc.exe
COLLECT_LTO_WRAPPER=e:/mingw_msys/msys.450x64v2/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.5.1/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../src/configure --prefix=/mingw_new --build=i686-pc-mingw32 --target=x86_64-w64-mingw32 --with-libelf=/mingw_new/build_libs --with-mpfr=/mingw_new/build_libs --with-gmp=/mingw_new/build_libs --with-ppl=/mingw_new/build_libs --with-cloog=/mingw_new/build_libs --with-mpc=/mingw_new/build_libs --with-sysroot=/mingw_new --with-build-sysroot=/mingw_new --with-system-zlib --with-host-libstdcxx='-lstdc++ -lsupc++ -lm' --enable-static --enable-threads=win32 --enable-languages=c,c++,fortran,objc,obj-c++ --enable-version-specific-runtime-libs --enable-leading-mingw64-underscores --enable-multilib --enable-lto --disable-rpath --disable-shared --disable-win32-registry --disable-bootstrap --disable-debug --disable-nls
Thread model: win32
gcc version 4.5.1 20100623 (prerelease) (GCC)