PS: Now that widgets can access personal user data such as Yahoo photo albums, calendars and address books it is possible for any developer to look at our new widgets and figure out how to tap into that data as well. However, please note that the calendar/address book/etc APIs that we’re using in these new widgets are not officially supported through the Yahoo Developer Network, so proceed at your own risk (or wait for the official APIs to come out).
Yahoo!—particularly their Yahoo! Developer Network, continues to open things up with abandon to third-party Web app developers willing to give the emerging Yahoo! platform a whirl.