> The thing is, I have used valgrind to get memory leaks out of slon as 
> far as I can. And if it is a general memory leak, the long-term runs
> I 
> am doing here at home should show "something" at least. Is it
> possible 
> that this employs a memory leak inside of the 7.2 libpq? Gotta check
> the 
> 7.3 and 7.4 release notes ...

It is possible. I built slony against a 7.2.5 source tree.

I wondered if it might have something to do with abnormally large tuples
(4MB+ in size), even if they are infrequent?

Have you tried a long-term run where there are several million entries
for a single SYNC ID?
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