We have built our own set of tools in a WinAVR-like layout suitable for use as a replacement. Please note that no guarantees as to fitness or suitability are being made. In particular,GCC 4.5.x has not been tested as extensively as GCC 4.4.x, so use our builds at your own risk.
For those building with AVR-Eclipse, a patch that teaches it about the new environment is available on the AVR Eclipse feature request tracker. To make life easier, I have a replacement jar available. Just copy it to eclipse/plugins after installing AVR-Eclipse.