Wow! Google Spreadsheet web app: very cool!
I have not spent too much time with the new spreadsheet web app but I did load a medium size Excel file, and everything went well.
The real thing here is shared editing with built in chat for collaboration.
I live in a remote area, so things like video conferencing, Skype conference calls, and now shared editing and viewing of spreadsheets all help reduce the business and technical costs of working remotely.