IMHO frid.ge was always a bit questionable, I personally built a comparable product and quickly realized that there is a huge amount of momentum around getting people into a system that is pretty much devoid of people you know.

Groups (and Events) are two features that Facebook has left somewhat sidelined over other feed oriented features. If they can get the mojo right on Groups then whole classes of me-too features (like frid.ge) are somewhat suspect. The interesting question is can you have a group that's coworkers who aren't your Friends, thus digging into Yammer is a serious way.