ZK - Open Source Ajax Java Framework

The second release of ZK Spreadsheet is implemented on top of Apache POI and enhanced with functionalities such as 3-D cell reference, user defined functions, JavaBean binding and more. Users can import Excel 2003/2007 files and collaborate online. The embeddable Ajax spreadsheet component is fully programmable in Java, with no plugins required.
Check out the features and release note. Click here for download.

Is the support for OpenDocument Spreadsheets in pipeline?

ZK, being an open-source software , should be supporting open-source standards first than proprietary formats.