I previewed BioShock 2 today, but I did not describe how the series' Plasmid powers have changed since the last game. Thankfully, MTV Multiplayer did.
Take it away, my former blog:
Scout An extremely unique plasmid, this allows you to basically turn into a ghost at will. In "ghost" form you're invisible, but you can still use attack plasmids (no guns, though). This means that you can scout ahead and zap unsuspecting splicers standing in a pool of water, or temporarily deactivate pesky turrets without threat of attack. Your physical body will remain in the same place, though, and you'll have to return to it to progress.
The MTV site has a run-down on six other Plasmids too. If you want to know some of the powers, check it out.
Guide To The New Plasmids Of 'BioShock 2' [MTV Multiplayer]