You Can Add Gadgets in Google Wave by Just Specifying The Gadget URL in XML form..
Here is The Step by Step procedure how you could add a Gadget for Google Wave .
As Soon as you Click on The New Wave Button, you will be able to see a wave box in the 3rd column of your Wave Homepage.
In Order to See The Link Gadget you Need to Expand the Wave Window
In the enlarged Google Wave Window, Locate The Gadget Icon and Click on it . A Box Pops Up Prompting for an URL Add Gadget by URL
While adding The Gadget URL make sure it is an XML file.
The Example URL which i have used is http://blah.appspot.com/wave/sudoku/sudoku.xml which is a Sudoku Gadget…
Once You Have Added The URL, You Could see The Corresponding Gadget and you u can add all your contacts to use the gadget all at Real Time!
Here is The List of Gadgets Available in Google Wave
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