Using this new feature in Ubuntu one can access Internet services using a desktop app, without opening any web-browser.
For installing ubuntu webapps in ubuntu 12.04:
Open Terminal and run following commands:
sudo add-apt-repository ppa:webapps/preview
sudo apt-get update
sudo apt-get install unity-webapps-preview
And, for uninstalling Ubuntu webapps run:
sudo apt-get install ppa-purge
sudo ppa-purge ppa:webapps/preview