An update to the 2K Forums by 2K Elizabeth tells us the DLC previously thought to be cancelled for the PC edition of BioShock 2 will be coming to the Windows variant of 2K's waterlogged shooter sequel after all (thanks joao via Rock, Paper, Shotgun). Word is to expect the PC edition of Protector Trials in December and the PC edition of Minerva's Den at some point after that:

We are a company of gamers making awesome experiences for gamers - and given the conversations we've had over the past two weeks, we've decided to go back and finish the PC patch and Protector Trials. Currently, we are patching the final bugs in these two pieces of content and then will submit everything to certification. The cert process can take anywhere up to four weeks, but as we hit major milestones (passing cert or otherwise included) I'll tell you guys. We are projecting that the patch and the Protector Trials will be ready to cert in December and I'm happy to announce that they will be available free to the community.

When we stopped development on Minerva's Den, it was not in a workable state and needed significantly more dev time to complete. As of now, we are not certain how much longer it would take to complete the project to our standards, but we have reallocated resources to work on completing the project so PC gamers can have this experience in Rapture along with 360 and PS3 owners.