Really the only issue that linux has to fix before it becomes more robot friendly is adding more Real Time Support.
Which more and more real time API is being added every kernel revision. 2.6.20 will be out some time in first quarter.
The advantage to linux is that it is a predominatly flat system. EG if you know linux for you laptop you know linux
for your micro controller. There are some minor differences (no Floating Point Hardware) but I'm using a Gumstix
on my robot running a light Debian linux and I'm running Ubuntu on my laptop which is Debian bassed, and every thing
is in the same place, and code compiles exactly the same (although I can't compile natively).