Great news
Aer Arann could introduce a feeder service from Belfast City airport where passengers could go through US immigration at Shannon and connect onwards to US services similar to the BA service from London City airport.
Aer Arann could also introduce an interline service to Dublin to connect onwards to Aer Lingus transatlantic destinations not served from Shannon, similar to what they do from Cork.
I think that Dublin and Belfast are the only 2 routes in Ireland that would be viable from Shannon.
Abroad, they could look at services to Paris CDG that CityJet are terminating and Amsterdam that Skynet used do. The ATR is a lot more fuel efficient than an Avro regional jet or 737 and both services would need to be interlining services to these hubs. In addition, they could be pretty confident that Ryanair would not fly to AMS or CDG.