Google slid a vector drawing add-on to Google Docs yesterday. It's more like a Visio than a CAD package. But it is semi-intelligent, with things definable arrowheads, vector text, and editable splines. There is an animation option I haven't figured out yet.
"Sketchy" is based on SVG for most Web browsers and VML for IE. You access it with the Insert | Drawing menu item.
I must've stumbled on it early, because this morning I found articles announcing the add-on at Techmeme.