Google Search by voice feature on mobiles allows users to search on Google through voice instead of typing keywords. Google voice search is already available for iPhone, Blackberry and Andriod phones, today Google announced the voice search for Symbian (S60) phones.
If you have a N series and E series Nokia phones you can use this feature by downloading the Google Mobile App from m.google.com. The software works with S60 version 3 for now, S60 version 5, that is touchscreen phones are not yet supported.
See the videos embedded below to see how it works
Via Google Blog