I just read the announcement that FreeBSD 6.0-RC1 is available for download. There's a helpful link on the new front page that directly points to places to find the new release candidate. The 6.0 schedule does not list a release date, but the RC candidate announcement says RC1 will be the only release candidate. I expect to see 6.0-RELEASE arrive within the next two weeks. Great work FreeBSD release engineering team!
FreeBSD 5.5, at least one more upgrade to the existing 5.x tree, is scheduled for arrival in November. According to the security advisory schedule, FreeBSD 4.11 will enter end-of-life status on 31 January 2007. After that date no security fixes for the 4.x tree will be officially provided. Support for the 5.x tree will end earlier, 31 May 2006. I believe the FreeBSD team is trying to encourage 5.x users to migrate, and leave a window open for people who have been running 4.x for years.