Well, I finally got it sorted out. There's a new version now, and it's available on the App Store.
http://itunes.apple.com/app/the-unarchiver/id425424353
If you can't or don't want to use the App Store, it's still available normally:
http://theunarchiver.googlecode.com/files/TheUnarchiver2.7.zip
The direct download version is still 32-bit x86 and PPC. The Mac App Store version is 32-bit and 64-bit x86. I'm going to put up the App Store version for direct download too later.
Other updates: