How to detect Postgres deadlocks?

Hi,

We are using Postgres 7.4.5, and I'm trying to find a way to detect and
gather deadlock information.

1) Which sql queries should I use to detect deadlocks while they are
happening? I see the deadlock info on the log file, but I'd like to query
the database to see them as they happen...

2) Which fields on which pg catalogs indicate a deadlock condition?

3) How can I get more info about the processes involved on deadlocks?

4) How can I get the sql statements associated with the processes involved
on deadlocks?

On the logs I see the procpids of the processes involved on past deadlocks,
but I 'd like to know how to get those procpids, and how to get the
"current_query" associated with them...

Thank you in advance,

Andre Philippi