The idea is that we replace bookmarks entirely with the tagging concept. Instead of bookmarking a page, subscribing to an RSS feed, you just tag it. Tagging an item automatically stashes that URL into your profile's tags file/database. If you're tagging a web feed, it automatically turns it into a Live bookmark (although we need to get rid of the "bookmark" term entirely...it's not a book).
As it stands, browsers are adding "there's a feed here" indicators to the address bar. Our browser treats that as a "Store this as a Live Bookmark" button (which is sort of unuseful, really). The initial idea is to add to or replace the Feed button (the orange thing) with a Tag button.