Slony-I is a "master to multiple slaves" replication system supporting cascading and slave promotion. The big picture for the development of Slony-I is as a master-slave system that includes all features and capabilities needed to replicate large databases to a reasonably limited number of slave systems. Reasonable, in this context, is probably no more than a few dozen servers. If the number of servers grows beyond that, the cost of communications becomes prohibitively high.
These details are provided for information only. No information here is legal advice and should not be used as such.