The failed installation showed up the following errors in the logs:
04/30/2009 09:32:06 8 INF Resource id to be retrieved is UpgradeTaskFailConfigSyncDisplayLabel for language English (United States)
04/30/2009 09:32:06 8 INF Resource retrieved id UpgradeTaskFailConfigSyncDisplayLabel is Failed to upgrade SharePoint Products and Technologies.
I tried various psconfig and stsadm upgrade commands, but nothing worked...
Anyway, it seems the Groupboard Workspace application was causing it to fail (as was the case with the Infrastructure Update last July) I uninstalled Groupboard 2007 from Add/Remove programs, and SP2 installed perfectly!
SP 2 offers numerous fixes and performance updates. One, I had a quick look at was the preupgradecheck.
Once you've installed SP2, goto a command prompt and type
stsadm -o preupgradecheck -localonly
after a number of checks the results will appear in the 12 hive\logs\ in a file called PreUpgradeCheck-
Both my farms are fine, except the fact they both failed on 1 point - the Servers in the farm aren't 64bit Windows 2008! which is a pre req for Windows SharePoint Service 4.0!