http://www.engadget.com/2007/10/31/buffalos-whr-hp-g54dd-airstation-router-comes-loaded-with-dd-wr/
DD-WRT is a fork of the original linksys firmware with many more features.
One of the main problems with it was that the Hardware drivers where not open source so compatibility with some versions of hardware was tricky.. If they have managed to get this into a retail product that must mean they have much better drivers available to them.
Hmm might be time for me to check out the latest release of DD-WRT again.