Gumstix is also quickly becoming the new standard for embedded linux due to their modules. Hopefully we will soon intergrate gumstix with Player to make controlling complex robots a very common practice for the average user.
Now, acroname or pololu needs to take this boards and integrate with working copies of player ready and motors/sensor packages.
If anyone knows of these initiatives, I would be happy to assist. Right now I'm working on a gumstix module involving a zworld rabbit 3400 with h-bridges and a simple sensor package.