This build replaces build 2162, and has a few 64-bit specific fixes in it. If you are running SQL 2000, probably a good idea to stick this on your server.
If you've been getting a lot of "Unable to read local eventlog (reason: 87)" entries in your event log with SQL 2005 RTM from the Alert Engine of SQL, you'll be happy to know this has been fixed in the new build.
Some installs never have it show up, others have it fill up the event logs. Strange little bug but I'm glad it is gone.