I forgot to mention it in the commit message, but this patch http://archives.postgresql.org/pgsql-committers/2006-05/msg00069.php includes a fix to avoid "tuple concurrently updated" failures in CREATE INDEX's update of the parent relation's pg_class entry. I'm still not convinced that that's where your problem is, however, because AFAICS that ought to be a pretty low-probability scenario. If that fixes it for you then there's something pushing the system to complete index builds at about the same time, and I don't see what that would be.
regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match