TV.com has a new iPhone app and there is lots of content for you to enjoy from CNET videos to Showtime to Star Trek and more. I did a search for Ellen and I was presented with past Ellen Degeneres episodes.
I tried the software over WiFi and it worked splendidly. I hear the quality is not as good over AT&T's network but that will likely depend on the broadband speed at your particular tower. Download it here.