If you go to anyone’s page on del.icio.us, the page title is now called “username’s favorites on del.icio.us” (here’s mine). Didn’t they used to call them “bookmarks?”
Update Feb. 9: it looks like it’s browser-related. If I load my page on IE it’s called “favorites,” in Firefox it’s “bookmarks.” I guess they scripted that in there so that you’d get a term you’re more familiar with.