Sun and Microsoft are about the only 2 large companies based on the proposition that Linux isn't the best operating system. IBM supports several OSes, but they strongly support Linux for most applications. HP & Dell are happy to sell hardware to run anything a customer wants to pay for, although they are both Windows-biased (and Dell continues to have serious trouble with Linux).

That's why I was so surprised and amused to discover that ILOM, Sun's Integrated Lights-Out Management system which is used to manage Sun's current x86 servers, is running Linux. So Sun is using Linux to make Solaris systems more reliable. I found a reference to Linux underpinning ILOM a few weeks ago, and still chuckle every time I think of it. I had a better reference, but cannot find it today.

http://docs.sun.com/source/820-0048-17/sp.html

That said, this was probably the right choice. Nobody's going to build a tiny system management system around Solaris, and rebuilding one and coping with the inevitable bugs in such a constrained and important system would have been a huge waste.