I don't have much to add to the "Google Office" discussion, except to add this note to Chris Anderson's plea for the ability to embed spreadsheets in pages like you can embed YouTube videos. We've actually had these before, courtesy of HalfBrain.com, which I wrote about back in 1999 during Bubble 1.0.
Written entirely in DHTML, Brain Matter provides the 20% of the functionality of Excel that 80% of the market uses 100% of the time -- all in your browser. It's fast, it's clean, it's intuitive -- and it's smart. HalfBrain clearly knows that when you migrate an application to the network, it opens up new ways to use that application. First, they've enabled network-based storage of the spreadsheets you create (of course). Second, their site helps shift focus from the tool itself to the use of the tool, by publishing more than 200 interactive calculators that help users do simple tasks like track expenses, plan a party or calculate the value of their options. Finally, they've flipped the viral bit, making it incredibly easy to email a spreadsheet to a friend, or to post a calculator on your own website.
The folks behind HalfBrain ended up doing a little thing called Oddpost, and you know the rest of that story...