Google's personalized homepage finally added the option to share a tab. If you click on the arrow next to the title of the active tab, you'll see three options: rename, delete and share. Google doesn't provide you a direct link, but it asks you to enter the email addresses of the persons you want to share that tab with.
The email contains a link that includes the URLs of all the gadgets from that tab. If you click on that link, you'll get a page that lets you add all the gadgets or only some of them to a new tab in your iGoogle page. Here's, for example, the link to my iGoogle tab about Google.
Google could generate a similar link for all your feeds and gadgets that could be used to backup your iGoogle page. After all, it's just a list of links.