I had an interesting situation back in January. I was called into a last minute minute meeting and asked to explain why I thought we needed JBoss and why websphere wasn't OK.
Frankly, I was stunned. I was told the meeting was to discuss what sort of hardware we needed and where it was going to be deployed.... Suddenly I'm asked to justify using JBoss instead of websphere to a bunch of fairly skeptical folks who where VERY interested in using websphere at all costs (for some reason).
Well, I stammered and stumbled since I wasn't really prepared to answer this and I could almost hear the folks on the other end of the call tapping their fingers on the table, waiting expectantly for my answer for them to instantly debunk.
I stopped for a full minute, my entire mind switching gears from "what sort of hardware/capacity might we need" to "why do you want to use JBoss instead of Websphere".
I then proposed the obvious thing (to me) "Well, Jboss is free".
Of course this was a ridiculous reason for using software. I was promptly schooled on how we would NEVER, EVER deploy FREE software, we absolutely MUST pay for it. After all, who would support it?
So I was a little bit shaken (not stirred) and had to think about it. To me, it is really great to be able to actually diagnose production problems by looking at the source code and figure out what went wrong. Most closed source companies don't really like you doing that (unless you pay them a WHOLE LOT of money).