Google has released a beta version of Google Gadgets for Mac. Google's Mac Blog provides some details about the release from Mike Pinkerton.
This feature brings hundreds of existing Google Gadgets to Dashboard. You can add fun gadgets (such as bowling, virtual flower pot, or YouTube), useful gadgets (weather maps, driving directions, and news), and others that offer daily wisdom for the ages (Confucius, horoscopes, and even a joke of the day!). These gadgets look and behave just like any other Dashboard widget, so you don't have to learn anything new.
Google's "Gadgets" are mini applications similar to Apple's own Dashboard Widgets. Google's Gadgets for Mac are now integrated and installable into Apple's Dashboard in Mac OS X. This makes them functionally indistinguishable from Dashboard Widgets.
Google Gadgets comes integrated with Google Desktop, a desktop search application also available from Google.