Although Google Docs & Spreadsheets is far from a finished product, Google already thinks about developers and intends to release an API that will increase the value of the tools.
"We definitely want to build out APIs, especially for the spreadsheets side, as spreadsheets are more data-oriented, but maybe also for he word processor. People will be able to do mashups with our tools for other things, and not be stuck behind our dev cycle for everything they want. If I've already got data somewhere you can't really rely on manual cut-and-paste to make it collaborative. Imaging pulling data from any application you've already got in use... you get that data over to the hosted app, make it collaborative, then bring it back... that's what we'd like to enable at some point," said Google product manager, Jonathan Rochelle.
The API could also enable users to synchronize data and use the information from other web applications.
Google launches Google Docs & Spreadsheets