If you want to browse the live schedule of events from your iPhone this app seems to be the best way.
There are several websites out there with the live schedule, including the official London 2012 site (which has a mobile-friendly design). But even that site is not as easy to use as the Live Extra iOS App.
And for watching the live streams from your iPad, this app is, again, the best bet. (Note that in order to watch the live streams you’ll have to sign in with the username and password associated with your TV service provider.)