Google announced on their mobile blog that they have put search option on google mobile while this features is already available on normal google search engine .
Available only in the US at the moment, and only for iPhone, Android and webOS, the Google Search Options can provide more relevant web searches than ever.
For example, suppose you are shopping at a store for a camera, and you would like to see what users have been saying about a specific model within the past week. You can do this simply by searching for the name of the product. Then, on the search results page, use “Options” to filter by “Forums” and refine further by choosing “Past week”. See the screenshots below for a sample query.