This is all changing though.
Shockingly, management are starting to buy the fact that we're getting screwed. We already have 25 Linux machines and a few postgres machines in production. They all run OpenJDK on them and infrastructure items such as memcached, Postgres, couple of MQ solutions. That and we've thrown TFS out, moved to mercurial+JIRA, have Eclipse on more workstations than visual studio and are not renewing our partner package next year.
This is what happens when you treat your customers like shit and force them through costly audits so they can pay you more money for not understanding very ambiguous license terms.
The funny thing is that MS built their business on comparatively open platforms (closer to the android model), but they've gotten too greedy and out of touch, I think.