The new iGoogle has been in beta testing for more than 2 months now. It was announced back in June that the new developer sandbox has been opened for a few Google accounts and not all are able to access it.
Several changes have been made like the tabs are now in the left side of the page instead at the top. They are expandable if you want to see the list of gadgets in a treet list. Another major change is that each gadget now has an expanded view providing more functions and features.