It would be incredibly boring for Google simply to replicate Excel and Word in a web format, unless you are an HTML groupie. However, there are some very, very interesting features that I think really turn the traditional office application on its ear. The first thing that caught my eye was the Google Lookup function, which allows one to incorporate search information dynamically into documents. The second thing was the Google Finance function, which allows financial information to be leveraged as well.  The third thing was the ability to embed portions or entire spreadsheets into a blog or web page.
Very cool stuff, and very interesting results. One could imagine this type of thing being leveraged with Froogle, Maps, or other service, within a document, presentation, or spreadsheet. Low cost, high reward stuff. However, there are some ramifications with using this type of information. For example, the spiffy new spreadsheet you put together for your boss could be modified by outside influences (like a Google Bomb).

Worth a look, at least.