Google has been working on using Cloud printing in their Google Chrome browser and Google Chrome OS. The Cloud printing feature allows users to add their current printers to the cloud and then print to it from anywhere.
This feature is currently in beta mode and it does not work many times. However, looks like Google is now trying to make this feature more mainstream by allowing mobile users to print their Gmail emails on the cloud printers they have setup in their accounts.
First off, the cloud printing technology is tied up to your Google account and you can set it up here. Secondly, you will have to leave the connected PC on for this to work. Thirdly, this only works with Windows based PCs right now, although support for Linux and Mac OS X is on the way.
Once you have set up your printers to the cloud, you can then visit Gmail.com from any mobile device and choose Print from the dropdown box to print a document. The document will be printed on the Cloud Printer you choose from.
The new feature is currently being rolled out to US English users only. There is no timeline on when this will be available for other countries and languages.