I was listening to Wait Wait on NPR last weekend and they mentioned a new study examining the effects of the Einstein video series. Basically, they state that children (infants?) that watched the einstein videos on a regular basis were slower in development than children that didn't. They continued to state that watching American Idol would be more beneficial.
I took a class about media and child development in college a few years ago that was very influential to me. The teacher spoke specifically about the einstein series and how they look like a great thing for infants to adults, but, like all TV, does not (and should not) replace face to face interaction with infants. We all know that the amount of tv watched by children and adults is appallingly high, but what's frightening is the amount of tv 'watched' by (or just on in the same room as) infants. How quickly and early children learn that the tv is the most important thing in the room.
I'm not a purist by any means. I probably watch too much tv myself and our laptop is on our kitchen counter, but i try to be aware of it, especially when it's around my toddler. I am surprised at how unaware people are about it. Much like politics, many people aren't making conscious decisions. They don't realize that their tv is on 8 hours a day (even if it's not being watched).