Scott Long says, the FreeBSD Release Engineering Team is pleased to announce the availability of FreeBSD 6.1-BETA4 and FreeBSD 5.5-BETA4. Both FreeBSD 6.1 and FreeBSD 5.5 are meant to be a refinement of their respective branches with few dramatic changes. A lot of bugfixes have been made, some drivers have been updated, and some areas have been tweaked for better performance, etc. but no large changes have been made to the basic architecture. The FreeBSD 5.5 Release is being done for people who are unable to make the jump to FreeBSD 6.X at this time. We do encourage people to make that transition as soon as possible, though. There have been some updates made between FreeBSD 5.4 and FreeBSD 5.5 but not all of the bugfixes done to RELENG_6 have been backported to RELENG_5. This will almost certainly be the last 5.X release.
We encourage people to help with testing so any final bugs can be identified and worked out. Availability of ISO images is given below. If you have an older system you want to update using the normal CVS/cvsup source based upgrade the branch tag to use is RELENG_6 for 6.1 and RELENG_5 for 5.5, though that will change later in the release cycle when we start doing the Release Candidates. Problem reports can be submitted using the send-pr(1) command. Read more.