An interesting take on the new data plans with some actual data information used to support it.
New iPhone, iPad limits: How far 2 GB will get you - Jun. 4, 2010
My takeaway, "For Netflix subscribers using the new iPad app, 2 GB of data will only get them between six and 12 hours of streaming movies and TV shows, depending on the bit rate Netflix used <snip>". Translation, ok if you're using it at home and can hop on a wifi network, perhaps pretty awful if you're traveling and planning to use 3G streaming to catch a couple TV shows.