Here's the creator's announcement thread about adflashblock-css:

http://talk.maemo.org/showthread.php?t=43753

It's called adflashblock-css, because it uses css to hide flash elements on the page. What you'll see instead is a white box of equal size to what the flash would have been and if you click the box, it will load / show the flash.

It doesn't use lists to look for ads - it just disables all flash content (or at least hides it).

You will probably only find it in extras testing (not sure), but it's a very small patch and, as far as I recall, only uses css to hide flash content and no "actual code", so it's lightweight and probably easy to get rid of if you don't like it.

I haven't measured how much faster sites got, but my gut feeling is that everything runs snappier on the sites I visit.