Reliance Net Connect , a venture of Reliance Communications , one of the leading CDMA & GSM Service providers in India website was Defaced by Hackers two days back. No reason mentioned by hackers but on deface page, Hackers wrote "Hacked by Dr-FreaK and Napsters Cr3w".
Defaced site link - http://reliancenetconnect.co.in , but at the time of writing this post, site has been successfully restored by company. But you can see mirror of hack on Zone-H.
Also in July 2012 Reliance Communications was successfully breached by another hacker with just information disclosure bug.