The new snapshot of pgAdmin3 V1.3 has Slony-I support included, with 
some limitations:

- Some cluster creation/joining cleanup pending
- Cluster commands like failover not yet supported
- Probably lots of bugs, please post them!

On the positive side:
Creating sets, populating and subscribing to them should be fully 
functional, node paths and listening too. I'm intending not to implement 
node creation, since joining a cluster should do that implicitely.

Check it out!

Regards,
Andreas