In Firefox3 beta the old bookmarks.html file (in your firefox preferences directory - e.g on Linux ~/.mozilla/firefox/somethingrandom.default/) has been subsumed by a system called Places which seems to consist of an SQLlite database in a file called places.sqlite - your bookmarks are imported into this database file on initial invocation of firefox3.
Firefox3 seems a bit snappier and I like the search in the bookmarks as you type in the address field. Also the tagged bookmarks seems handy but I wish they would allow you to know the folder in which your found bookmarks reside - the locate in bookmark folders plug-in doesn't work any more..
