Add Google Voice to Gmail
You can add this Google Voice gadget to Gmail’s side menu by enabling the “Add any gadget by URL” feature in the Gmail Labs settings. Then just add the gadget’s URL by going to Settings > Gadget. The URL to paste is:
http://hosting.gmodules.com/ig/gadgets/file/103004048084238050439/GoogleVoice.xml
It was designed for iGoogle, if you want to use it there however use the following URL instead:
or a smaller version of the same thing, all I did was adjust the height for gmail.
http://hosting.gmodules.com/ig/gadgets/file/112816433133071246574/mini-GV-for-GM.xml
Ignore that last post, google mobile changed their mobile page, which means a gadget that works well will take a little more effort. Someone should be able to figure it out with a little JSON and XML coding. Check out the source file for the firefox extension for some hints, and also, using Xpath might work too. Who knows.