Most of their devices act as bridges; some of the newer ones don't. Some have multiple ethernet ports, and anything that has both an ethernet port and is part of their "sonosnet" mutant-wifi will bridge between sonosnet and their ethernet port(s) with spanning tree using classic (pre-RSTP) link costs.

If you're not careful you can end up with the "best" path between two switches going over the sonos-to-sonos wifi.