from Ars Technica:
Editing is straightforward enough, and not noticeably different from working in good old MS Word or OpenOffice. Tables, images, the ususal lineup of fonts—it’s all there. The right-click menu tends to be obscured by the browser’s equivalent. That’s slightly annoying, but you can work around that by hitting ESC once, and the menu isn’t all that useful to begin with. You’ll likely do fine with just the toolbar buttons and pulldown menus at the top of the editing window. The usual keyboard shortcuts work, too—CTRL-S for save, CTRL-Z for undo, et cetera.
The most notable feature of the editing process is the AJAXified collaboration. You can invite others to co-edit your document and see their additions or subtractions with a slight time delay, live in your window. The editor autosaves every ten seconds, which pushes out changes and pulls down new versions from the central repository. That could certainly come in handy. You’ll also always see who else is working on your document right now because they’re listed at the bottom of the screen. Writely keeps a revision history, and you can revert to any earlier version you like.
When you’re done editing, you can download the document in .doc, .rtf, or .odt formats, as a PDF file, or as a self-contained zipped HTML files with all images included… You can also publish the document and send a link to whoever you want to read it, or publish an RSS feed of document revisions.