Hello gurnani,
I'm hoping that the FiOS Mobile app will be improved soon to allow viewing of live, on-demand & DVR'd shows all through that single app instead of having to install an app for each of the thousand+ channels. Verizon has been promising an updated version of the app to work better (read: not crash) on iOS 5 but seems that fix has been delayed.
In the meantime, I've had success with the Watch ESPN app for the iPad 2 to watch live TV using my Verizon FiOS account. I was able to watch a NASCAR race as well as football games - even replays of golf games for my father. Give it a try...
Craig