do you have any extensions installed? but yes, i have similar experiences. here's a screen shot of Chrome:
4 tabs open (MR, ArsTechnica, Youtube, a watch forum)
4 extensions installed (Adblock, Ghostery, Xmarks, Tracktor)
FF4 is way worse. 2 tabs and 3 extensions ate 500 mb right off the bat. Safari is all right... but i don't like the tab management when compared with Chrome/FF so i don't use it much. great to see that some light surfing on the internet demands just as much, if not more, memory than when i'm working in Lightroom and Excel with rdio running in the background.
and for those commenting on fresh installs, i just bought this laptop... maybe 5 days ago? it's about as fresh as can be.
I have Adblock plus, xmarks, and speed dial. Nothing out of the ordinary. Right now Firefox is open with 9 tabs and it's taking up 1.03 Gb of real memory. I saved all tabs, quit Firefox and reopened the saved tabs and now it's taking 400 mb of memory. If that's not bloat, I don't know what is. Too bad it's the most compatible browser in my experiences.