Hi,
I can confirm that multiple panStamps can communicate between them and also to a common receiver. panStamp follows a point-to-point and point-to-multipoint schema. Moreover, there is Lagarto, an open source automation platform which lets us do many things from the IP world, including sending data to multiple clouding data services (Cosm, ThingSpeak, sen.se), integration with OpenRemote, event management, web GUI, etc.
Did you take a look at panStamp's documentation wiki? Google Code Archive - Long-term storage for Google Code Project Hosting.