I know the GroupWise driver can sync to multiple PO's. Can it also sync to multiple domains? I don't see how it can since you select a single wpdomain.db file in the driver configuration.
One driver can sync to multiple PO and multiple domains. GW replicates updates sent to one domain to all other domains in the system. Every domain DB has the info for the entire GW system. The only reason to use multiple drivers is if the eDir tree is partitioned such a way that GW objects are divided between partitions.