According to the official Bioshock website, Cult of Rapture, there will be both a bug fixing patch and some new DLC coming for both versions. The Xbox 360 update will be available either as an auto-update or via the marketplace if the content is not included. The PC patch will be available at the Bioshock homepage. Here is an excerpt:
Both the BioShock PC Patch and the 360 Title Update will be available next week. In addition to these fixes, we will be releasing downloadable content free on both Xbox Live and for the PC, with the DLC bundled into the PC Patch. A full list of bug fixes and everything included in the DLC will be put up on the Cult of Rapture when the downloads become available.
People who have intimate knowledge claim that the content will not be new levels but new plasmids that were omitted in the final version of the game. We will let you know the minute we get word the update is available.
I just downloaded the new free plasmid pack on Xbox Live. Can’t wait to use it
Ahaha no way I can’t beleive its out. I’m going to download this as soon as I get home.
[...] Yesterday, we brought you the news of the Bioshock patch. Here are the details. First, there will be 4, yes 4 new plasmids. They are as follows: [...]