A screenshot of FF 3.x eating well over 600 MB of RAM on my system. Thereby moving my RAM usage from 33% to over 60% at the moment.
I discretely remember reading several tech sites reviewing FF3 and saying that it eats only 200 MB of RAM. Bogus. I call it a lie!
So there ya go. Firefox eating over 3 times the advertised amount.
P.S. I do have 26 open tabs right now. That number usually jumps between 14 and 48.