Do you think it's okay to read picture books with your 2 year old child, or use other simple interactive devices like a See 'n Say [0]? If not, why? If so, what distinction do you see between those and supervised iPad usage? It's not like a 2 year old is going to be using the iPad unsupervised and accidentally browsing to inappropriate material as is possible with unsupervised TV viewing.

[0] Those circular toys that play animal sounds. http://www.fisher-price.com/fp.aspx?st=10&e=sandslanding