Vaccuum allows read access?

I could have sworn I saw a post where you (Tom Lane) figured out how
to get tables to be read-only while performing a vaccuum rather than
being completely locked.

Is this true?  Is it in the -PATCHES branch?

thanks,
-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."