Adobe Story is a (currently free) Software as a Service using Adobe Air.
I started conversion of the 8 minutes of script that I had in Google Docs to the more refined format of Adobe Story that Premiere and After Effects will be (well, is advertised to be ) able to use natively when CS5 comes out (which I plan to get ASAP).
The process took very little time. I’ve used script writing software in the past so I was familiar with the standards tab, enter, etc for shorthand scene and character headers… it worked very fluently in comparison to the others (CeltX & Sophocles* are the two I’ve used).
There are some collaboration features that I wish that I could have tested it out, plus there’s an Offline Mode for writing on-the-go which appears to sync back to the server once you’re online again (assuming you install the Air portion of the software).
Overall I’m impressed. It was a bit sluggish at the time because it was running on a Flash platform (mainly when waiting for the Character/Scene popups for auto-complete and very much so on initial loading of a script), but overall I’d recommend it to anyone who’ll be using Adobe for any part of their production.
*Sophocles’ website seems to have changed hands since last I’ve looked. This is unfortunate as it was pretty good software and the developer was awesome.