I don't really think this has all that much to do with renewables, and everything to do with using their market share and data mining resources to build demand response capacity. Simplifying a little bit, in a power market (like Texas's ERCOT or the Midatlantic's PJM), you can "bid" a reduction in capacity/energy use into the market the same way a utility running a power plant can bid actual generation. Utility companies already have programs which lower your thermostat, cut off your water heater etc etc, it wouldn't surprise me if Google was attempting to do this on a larger, commericial scale.
Google currently has their "PowerMeter" service as a monitoring tool, but this could be expanded to a remote demand-response application (like Utility DR), allowing them to aggregate residential and small commercial customers. With their data mining abilities it won't be hard to accurately predict how much reduction in electricity demand they can actually get (how much you actually can handle your AC being turned down, not how much you say you will), and they can bid that demand into the power markets.
I recently worked at a utility which was concerned about a Google and/or Wal-Mart entry into the power markets. Why? They both have the name recognition and infrastructure to develop/market these programs to huge customer bases and undercut the current efforts. Interesting that this could be their big first step towards that.