Just so you know, I have an open source alternative to stackexchange and we do free hosting too http://shapado.com we also import stackexchange sites (beta).
i have one of the bigger stack exchange sites...and I'll be moving to Shapado if Stack Exchange kicks me off. I was already looking into them, since their rates were almost 3 times cheaper $50/1mm page views vs SEs $129/1mm pageviews.
If you don't let the admins make money, there is no reason for them to bother building a community.
If you don't let the admins make money, there is no reason for them to bother building a community.