Hi,
We did about 250K impressions during the first month (actually slightly less than 3 weeks) and made almost $100.
The CTR on our board is very low (0.14%), but on the site it is much better (3.35%).
As this pretty much pays for our bandwidth costs, I am quite happy with it.
There was some bitching when we introduced it (mainly because I stuck on the sidebar which I introduced at the same time), but it seems to be accepted now.
Sanuk!