1Up has put together a detailed three-page preview of the first couple of hours in Irrational Games' BioShock. Obviously that means a few spoilers might be sprinkled within:
You also learn the art of hacking. When you want to do anything from lessening the prices on goods you find in vending machines to turning gun turrets against enemies, you can choose to enter an optional minigame where liquid flows through a pipe on a grid and you have to line up the proper parts of the pipe to get that liquid to the proper exit point before time runs out. You can also get an autohack if you don't want to bother with this, but there doesn't seem to be much punishment for failing a hack so you can always try again.