I'd be more likely to nag you about the keyboard-unfriendliness... the reset you mention is likely where the focus outline got removed, since most of the popular resets out there do that (with a snarky comment saying "don't forget to put it back in" that everyone ignores).
As a laptop user I can't tell where the heck I am with my cursor as I tab through the menu or the page... I have to rely on looking at the little bar at the bottom of my browser.
Since you're using sprites, it ought to be easy enough to add the :focus statement to every place you have :hover. Then outline can remain safely gone (well, except for IE but I expect IE users to be used to the inaccessibility of that browser).
Facebook is NOT a good example of code. They are built out of a steaming pile of script-ridden gar-bage. It even thinks one of my browsers is a mobile phone and sends me to some wap page. Facebook is popular not because it works for everyone or is well-written but because it works for many people and they like the idea of a site suggesting people as friends whom they haven't seen since childhood and have no obvious connection to them which is downright creepy (but also strokes the ego as well).
Felgall stated that if a page or app doesn't work for many people that the site will lose popularity as people tell their friends etc. Facebook is proof that this isn't true. But, I do hope that Facebook tries to act more like Amazon, who DOES do usability studies and DOES make everything work like a website should (and yeah they also have spaghetti-ness in their code and validation errors... so I do agree it's more awesome to have a site WORK than be 100% error-free).