Postgres: We're making steady progress toward the 8.1 feature freeze. Perhaps I'll jinx it by writing this, but it seems that people are paying more attention to the feature freeze date (July 1st) this time around. There is the usual flood of large patches as the freeze date approaches, but it seems a bit less hectic than it has been in years past.
Slony: I don't have anything I need to get in by the freeze, although there are a few patches I need to review. I'm spending most of my time these days working on Slony II (the synchronous multi-master database replication system for Postgres that I'm working on with a few other folks). We haven't been talking much about Slony II -- not because there isn't work being done on it, but I think there's a consensus that we don't want to hype something that hasn't even been completely designed yet, let alone implemented. Still, I'm hoping to get a prototype of the system finished by the end of July that can do multi-master replication of arbitrary DML in serializable isolation level. Hopefully the prototype will also include some basic recovery functionality as well ("recovery" is how we synchronize the state of a joining node with the current state of the cluster). Once the system gets a little closer to reality, I'll post some more about the design of the system.
Robert: Yeah, the Postgres-R (SI) work is one of the papers we have been considering for Slony II (there's a copy you can get here that doesn't require IEEE membership). The current prototype we're working on will be fairly similar to what Prof. Kemme proposes, although I don't think we've decided that this is definitely the right way to go.