In portage as net-wireless/acx100, its a class of wireless NICs based on TI's ACX1xx chipset. This is for x86, amd64, and on the next version, for PPC, too.
And heres a helpful device matrix: http://acx100.sourceforge.net/matrix.html
This has been added to the template specs for x86... others will follow if the package is marked stable on their arches...
We had to remove support for this driver at the last minute, as it was preventing us from being able to build the release.
This is fixed with the 2005.1-r1 release media.