Until what time are metro and busses avalliable in Berlin?

On weekdays the metros are available until about half past midnight, on weekends until 2 in the morning. Some metro lines run all night.
It's pretty much the same with the busses, but they have a special night schedule for them, meaning about every half hour there should be bus leaving a station.

Behind this link you'll find the website of the public transport (BVG). It's in English.
http://www.bvg.de/index.php/en/Bvg/Index...

Otto, maybe you should also mention that metro service starts at around 5:00 to 5:30 in the morning, and there's night taxi service available at comparatively cheap rates. So finding oneself lost out in the sticks in the middle of the night is very much improbable in Berlin.

During the week metro (U-Bahn) service closes at approximately 1 o'clock (depending on the station and line of course!) and starts again at appr. 4 to 4.30. Buses go through all night each half an hour.
At weekends public transport in the inner city (including metro of course) runs all night every 15 minutes.
Btw: Metro in Berlin is U-Bahn, don't mix it with the Berlin "M" (Metrobus, Metrotram), as it stands for special, faster Buses and Trams!