Source: http://www.labnol.org/internet/search/google-tinyurl-service-for-sms-search/3926/
When you perform a web search on mobile phone using Google SMS, the SMS text message you get back from Google has two parts - web search results and a short URL that redirects to the relevant Google search page.
For instance, Google sent an SMS message with this short URL - m.google.com/u/xva9Ot - for a search query like "Global Warming."
Now if we to use the services of TinyURL for converting that same Google page into a shorter URL, the resulting address would be something like this - tinyurl.com/6xbo7q.
Noticed a similarity ? The redirection code generated by TinyURL (6xbo7q) and Google SMS search (xva90t) have six characters each.
Since this can just be a coincidence, let’s look at the HTTP Response generated by Google that clearly says "tinyurl_server."
Google is either using TinyURL service for generating short URLs or there’s another possibility - they may have developed something similar in-house but gave it the same name "tinyurl."
Related: Google Should Consider Decoding TinyURLs
Google Using TinyURL Service for Shortening URLs in SMS Search? - Digital Inspiration by Amit Agarwal