On a side note, this is why the iPhone's Safari is far and away the best mobile browser at the moment.
Simply double-tap the paragraph or column of text you actually want to read, and the browser will zoom in so that all the annoying, animated ads (and really, everything else excepting the content) are pushed off the screen and out of your field of view. Now, I will grant you that having an ad-blocker would be superior, as it would prevent the downloading and execution of such ads in the first place and save my battery life, but the high-resolution zoom is so effective that I can live without the blocker. The iPhone doesn't produce any hover events, which is a mixed blessing, but in this context it means that those annoying embedded keyword ads won't ever activate.
Until Fennec is release-quality, anybody trying to avoid ads on the go should look into the iPhone or iPod Touch. For the record, I use a Nokia E71 every day, but its mobile browser crashes so often it's basically useless. I carry an iPod Touch and seek out WiFi, or tether my laptop to the phone when I need to browse.