londrum - 1:10 pm on Apr 19, 2011 (gmt 0)
it might not have anything to do with the ads, though.
maybe your page speed has improved now. that might improve your page views, repeat visits, visitor retention and lots of other stuff. google would measure all of that.
if you improved your page speed in other ways, but keep the ads as they were, then you might have seen a similiar improvement.