We are excited to open up an updated Themes API for developers to customize new features coming to iGoogle. Features you can modify include the left navigation and UI updates introduced in the iGoogle developer sandbox in April, as well as the chat feature that was released to the sandbox last week. If you have already created one of the 800 themes in the iGoogle directory, make sure to update your theme with the latest attributes and resubmit.
You can more details in the updated developer's guide. We're hoping these feature additions will allow for developers to customize even more of iGoogle.
As always, questions and feedback are welcome in the Google Themes API group.