I agree with Lakitu, everything in moderation.
My daughter is 2�, my husband and I watch kids TV with her and talk to her about the programmes she watches. We don't just 'dump' her in front of the TV on her own. She can now count to 20 in Spanish and say a few Spanish words thanks to Dora the Explorer & Go Diego. There are some great kids programmes out there that help kids learn about all sorts of things in a fun way, in addition to learning from parents and other sources.
And like tigwig's daughter, she's getting a bit too familiar with the Sky remote and Sky Plus!