> Firefox by default wont find favicon.ico by reading a HTML/XHTML document and looking for a <link rel> pointing towards it

Are you sure? I was under the impression that if you have a <link> tag to the favicon, this would be used an no other accesses made. Furthermore, I know the favicon is quite aggressively cached, so that if you change your favicon, it's very hard to get Firefox to reload it - shift-reload won't help, for instance. A cache clear might be required before it reads the new one.

I've heard a lot more complaints about IE looking for favicon files, on the other hand.

Of course, I haven't done any real tests of any of this. Anyone else have some hard information?