Limiting number of connections to PostgreSQL per IP (not per DB/user)?

Hello!

Sorry for that subscribe post I've just sent, that was bad reading on my
part (for the subscribe info on the homepage).

Anyway, the title says it all: is there any possibility to limit the
number of connections that a client can have concurrently with a
PostgreSQL-Server with "on-board" means (where I can't influence which
user/database the clients use, rather, the clients mostly all use the
same user/database, and I want to make sure that a single client which
runs amok doesn't kill connectivity for other clients)? I could surely
implement this with a proxy sitting in front of the server, but I'd
rather implement this with PostgreSQL directly.

I'm using (and need to stick with) PostgreSQL 8.3 because of the
frontend software in question.

Thanks for any hints!

--
--- Heiko.