Saw two new EMB 190s in the takeoff lines today in ATL. We saw one waiting to take off on the south side when we were landing, and one taxiing on the north side when we pulled up to our gate. They were painted in EMB colors with EMBRAER 190 painted on the side. Im guessing they were making timing/practice runs into ATL, but from where to where and for whom?? JEtBlue?, Delta? Anybody?