Firefox 3 Alpha 5, slated for a release next week, will include some form of the much awaited bookmarks revamp known as Places: "we are excited to let you all know that last week we enabled the Places implementation of bookmarks on the trunk". The team would also like to emphasize to make a backup of all bookmarks, just in case. As well, once the migration of bookmarks occurs, all changes to bookmarks will be kept up to date in Places. That means that changing bookmarks or adding bookmarks in an older version of Firefox will only be seen in Places if they are manually exported and re-imported into Places. It should be noted that the UI is still being designed in terms of both functionality and performance. In addition to bugzilla and the newsgroups, a good way to contact the Places team is to head over to #places on Mozilla IRC.
News source: Mozilla Developer Center