This observation from Urbi has been true since at least late 2007, when posting at .org surpassed posting at the original, defunct Prosper forum.
Of course, "community" is not an important word at Prosper, just as "transparency" isn't. Prosper went out of its way to destroy the community, by banning members and suspending their accounts (remember Epictetus? He got banned for doing absolutely nothing), threatened to sue its community, and badmouthed the community to others...
Yet that same community once was very active and even protective of Prosper. They could have been a great resource (as they once were), a lot of companies wish they could have the active interest Prosper once got from its members.
Such a shame.
One could speculate that a whole new community may develop, independent of this one. But I see it as unlikely; the demise of groups and automation of bidding has removed the most compelling reasons for a community to form.
At any rate, .org really is the closest there is to any vestigial Prosper community, such as it (and .org) are. Even it is fragmented and fading... There really isn't much to get excited about anymore.