Google bought Jotspot
Google has acquired wiki service JotSpot (see news story.) Jotspot is one of a few wikis that's easier to write in than the first generation of wikis. Early wikis required you to write your links and formatting in wiki code, which is quite straightforward, but also quite different from standard HTML and from working with a WYSIWYG word processor, like Word or Google Docs. The newer WYSIWYG wikis (WYSIWikis?) make creating a group document almost as easy as working in a word processor.
Which begs the question: Where does a word processor end and a wiki begin? Google Docs is already a great collaborative editing tool. It even has a revisions history function, like most wikis do. What it doesn't have are capabilities to create a web of pages, nor insert interactive elements (like polls, comments, mini-spreadsheets).