Though this varies according to the laws of the state and the customs of the local jurisdiction, penalties have become very tough in the past few years. Generally speaking, a conviction for a first offense may involve a fine, a license suspension or restriction, attendance at a DUI education course for a period of time, and probation for perhaps three years. A short jail sentence of only 2-4 days may or may not be required; for a second offense, it almost certainly will.
Additional punishment may involve community service, ignition interlock devices and/or impounding of the vehicle.