To do a Google search in Persian, you go to www.Google.com/intl/fa/ (Google in Farsi) and beside the search box you will see a small keyboard icon. Click on it and a Persian keyboard opens up on your screen where you may enter your search phrase using Persian characters. You can do the same for Russian or Thai by going to Google.ru or Google.th . Currently there are 35 languages supported for this function. Unfortunately Mandarin and Cantonese are currently not available with this feature, however I am certain Google will add these two important languages very soon.
Speaking about the virtual keyboard, it is worth mentioning that Google has has also updated the Translation function. This feature now offers both written and audio translation for the 35 languages that are supported in the virtual keyboard function (plus Mandarin!)