I notice that in google mobile search result a small green mobile icon is showed for some sites indicating mobile version.But all sites does not seem to get so in the search results.For example mashable.com has mobile version of its site but green icon is not shown but say for labnol.org a green mobile icon is shown,Similar many blog have mobile version but they dont seem to get that mobile icon in search result.My site is powered by wordpress how to get such icon in result.And my site is made ready for mobile users.

But how to get such mobile icon in google search result that's what i want to know...

Examples

<http://img857.imageshack.us/i/googleresultmobileicon1.jpg/>

<http://img836.imageshack.us/i/googleresultmobileicon2.jpg/>