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, bleeding-edge releases of GCC have not been tested as extensively as GCC 4.4.x, so use these 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.
Download and run the installer (.exe on Windows, or .runme on Linux & OSX) from the releases at the bottom of this page.
The following packages (and their dependencies) are included in Inferno Embedded AVR Tools.
Install XCode from the AppStore and then start Xcode and use Xcode->Preferences->Downloads to install component named "Command Line Tools". The tools will be in /usr/bin folder.
Install GCC 4.7.1 from https://github.com/sol-prog/gcc-4.7-binary.
You can view the changelog and source code online in our git repository.