On MySQL developers zone there is a quick poll on which operating system you use.
The combined results of all Linux flavors accounts for 50% of the answers so far. What surprised me is the 6% of mac OSX used as a server. My own experience with macs is just as desktop or laptop. In my very personal view, it feels like a waste to use such a beautiful thing like a Mac as a server. Linux, as Neal Stephenson put it in In The Beginning Was The Command Line is like a tank. Efficient but not appealing, compared to Macs, which are described as stylish cars.
So, if business is a battle, the Linux tank seems your best bet to get out alive when the smoke settles. The funny thing is that Solaris is an even sturdier tank than Linux, and it should deserve more attention. I guess that, being a recent contender in the open source arena, it will have to pay the price of the learning curve. A price that Linux has paid long time ago and now is reaping the fruit.
If you disagree, have your say!