iGoogle (and Orkut, and Wave, etc) all use Apache Shindig to power their gadget sites.
There are a number of iGoogle specific extensions that are not part of Shindig so it is not 100% compatible. Also the default Shindig container implementation does not support UserPrefs very well.
However this will get better soon. Google is contributing what they call the 'common-container' to Shindig, which will make it more compatible and capable.
iGoogle (and Orkut, and Wave, etc) all use Apache Shindig to power their gadget sites.
There are a number of iGoogle specific extensions that are not part of Shindig so it is not 100% compatible. Also the default Shindig container implementation does not support UserPrefs very well.
However this will get better soon. Google is contributing what they call the 'common-container' to Shindig, which will make it more compatible and capable.