The Linux/Unix blog has an interesting little piece on the Mars landers that I doubt we'll see in the mainstream press. It turns out that NASA used Linux to run the Mars Lander, not software from another well known vendor.
"When NASA needs an operating system for a Mars lander does it go knocking on Bill Gates’ door? The answer is no. The newly arrived on the planet Phoenix Lander is powered by a variation of Linux running on a specially hardened CPU and motherboard produced by IBM."
Apparently they used special hardware, too. Hardened to operate in the harsh environment twixt us and ... there. Not that that's a surprise, I suppose, but interesting none the less.