FireCore has surprisingly released a new version of aTV Flash for Apple TV 1 making it an “all-new platform for running the latest XBMC version 13.2 (Gotham)”. It includes support for the latest video add-ons, 1080p video, and more.
aTV Flash (xbmc edition) is finely tuned, optimized for speed, and provides a complete replacement for the standard Apple TV software.
The new version is different from the original aTV Flash (silver): while the older version installs add-ons alongside the native Apple TV software, aTV Flash (xbmc edition) replaces the Apple TV software entirely.
Each serves a different purpose, but if your main goal is to get XBMC on your Apple TV then aTV Flash (xbmc edition) is the one you want.
According to the developers, installation is done in about 5 minutes using a USB flash drive. They have also built in a special restore option, allowing the original Apple TV software to be easily reinstalled at any time.
By installing a special 1080p video card, the original Apple TV will be fully capable of playing most 1080p formats. 1080p video cards are available as an optional add-on when ordering.
Note: Installing a 1080p video card replaces the standard Apple TV Wi-Fi card. A directly connected ethernet cable or USB Wi-Fi adapter (also available as an optional add-on) will be required for network access.
You can find more details on aTV Flash (xbmc edition) here.