Tip of the hat to Alex for highlighting Scripped, a web-based screenwriting app, along the lines of Google docs, and the 37signals portfolio.
Scripped is, to be fair, pretty bare-boned, but not quite as minimalist as the similarly web-based ScriptBuddy - it at least has an export to PDF function (ScriptBuddy makes you pay for this privilege) and a much more streamlined interface. It also has what looks like a pretty decent draft management system.
Of course, for all their potential networking features, remote storage and platform agnosticism, the downside of all server-side apps is that they can only be used when you’re online: handy in a fi’d up coffee shop, not so useful on public transport. And feature wise, they can never compete with dedicated desktop apps such as Montage (my own preference), Scrivener (superb for organising and drafting documents), and the increasingly capable Celtx (FREE!); and that’s just on the Mac.
Still, I daresay Scripped will find an enthusiastic audience of admirers, and good luck to them. I’m sadly still an old-world paranoid who dreads the thought of his data in another man’s arms, and will remain wedded to my hard-drive apps for as long as they’ll have me.