They already run PadLister[1]. I wonder whether their endgame is to usurp Craigslist, or to continue being an aggregator? Personally I see more value in them pulling in Craigslist ads than trying to create their own community, but at this point they're really limited for options.
Maybe I'm looking at this the wrong way, but what about companies like Twitter that rely heavily on people using their API? Is there ever a concern that the apps will try to create their own network and push Twitter out?