As others have said database management is in high demand now. Businesses will fight tooth-and-nail to protect their databases and this take priority to any operating system they might use. Looking forward I see the biggest growth opportunities in Linux particularly now that IBM offers a Linux NOS for it's mainframes. This way mid-to-large size companies can put their mainframes on Linux and run their distributed neworks with the appopriate Linux distrubutions for each level. Imo, this is a 'really cool' solution and will save a Tremendous amount of money, time and energy going forward. Intel recently switched to Linux and estimated their savings for the first year alone would be $200 mil.
When there's a problem with a MS OS there's maybe 15 people in Redmond, WA to locate, troubleshoot and patch the problem. When there's a problem with Linux there's literally 10s-of-thousands of programmers worldwide to find and fix the problem. Furthermore, they'll do it in the shortest time possible and provide the fix to apply across all affected platforms and versions. This is one of the main benefits of open source vs. closed source OSes. Linux people can i.d. and fix their systems as a community whereas MS people have to wait to see what Uncle Bill will do for them.