Log files, how to rotate properly

I just ran into an interesting problem. My /var partition was full, and the
culprit turned out to be the postgres log file, which was only evident
through lsof. It was actually a deleted file which was being kept open by
the running process.

The interesting thing is that if I redirect the output of postmaster, then
every connection has this file open.

My environment is Apache/jserv/postgres. So in order to rotate the postgres
log, I would have to

1) Shut apache down,
2) Shut jserv down
3) Shut postgres down
rotate the logs, then bring them all back up again

Is there a way to tell postgres to release the log file, or am I completely
off base here?

Dave