The goal of the SocialCalc project, as described on the Software Garden OLPC Home Page, is “to provide a capable, simple spreadsheet which runs locally on your computer”.
Software Garden is involved in the project of Socialtext, Inc., to provide a system based on a new version of the SocialCalc spreadsheet code on the OLPC XO-1 computer that is being called “SocialCalc” on the One Laptop per Child – OLPC initiative.
The main engine is written in JavaScript and is available under Open Source licenses. Much of the code, being written in a common scripting language, should lend itself to examination, reuse, experimentation, modification, and extension.
The latest version and its documentation is free and is downloadable from the page link above.