That's not how government procurements work in my line of business. Actually, the contractors for the most part suggest and make the purchases. That's really because we simply have our finger on technology more so than the civil servants.
It's nice to see that governments are starting to see the viability for linux. On my contract, we have been using Linux for clustering for several years - and that's simply not going to go away. And of course now that SGI and CRAY have linux offerings, it will only get better for us linux geeks in the HPC arena.