J.A.R.V.I.S. debuts as the AI that runs Tony's house and his Iron Man suits.
J.A.R.V.I.S. flies the damaged suit, with Tony inside, to Tennessee after the house is destroyed, and later remote-controls dozens of Iron Man suits in the final battle.
The workshop helper from the first film ends up doing the flying himself. By Iron Man 3 the suits can fight with nobody inside them.
Source: Wikipedia: J.A.R.V.I.S.