TonidoPlug: Platform for a low-cost calendar server?

I'm still looking for a low-cost, low-power, quiet calendar server, and may have found a candidate: the Tonido Plug. Click around until you can read about Tonido Workspace, which includes a PIM. No mention of CalDAV or other calendar-sharing capabilities, but if the platform takes off -- and it has some rave reviews -- I'm sure one could be built. Not sure it has much momentum though. Maybe this will help.