Same issue here. Seems that all cache and cookies were wiped out with the update. Being a software engineer myself, I have to say, it's generally considered very poor practice for software updates to wipe out user data. It's very surprising that this would happen with Mozilla.

Unfortunately, I'm trying to get everything back to how it was for an elderly family member, and she has no clue how she got it set up to begin with. I'm pretty sure that she didn't have an iGoogle account?

I found my "gadgety" home page again, but I think it was via the iGoogle acct: from the plain vanilla google.com page, the menu at top has at the far right "more. . ." and under that, the bottom item is "even more. . . " and that takes you to a page of menu items, Google products:

http://www.google.com/intl/en/about/products/index.html

When I clicked the "iGoogle" link, all my stuff reappeared. So maybe the iGoogle acct is key. Good luck!