A quick internet search didn't lead me to the actual Harvard Study regarding babies and TV (but if I find it later, I'll post a link). What I've found interesting is that there are two decidedly different slants on the study. Almost every article online has a title along the lines of "TV Does Not Boost Babies' IQ"...OR.... "TV Does Not Harm Babies". Occasionally you may run across a completely neutral title like this one.
Baby Einstein probably really started the craze of getting people to buy into television as a educational tool for babies. Parents everywhere swear their infants were mesmerized by the DVDs. I was always suspect of DVDs for babies. Like most everything, it's probably all right in moderation. But, in my world of thinking, a baby who is raised on Baby Einstein will eventually move on to other TV shows or movies and before you know it, you have a six year old who watches 4 hours of TV a day.
For sure, my son watches TV and definitely more now at 18 months old than he did a year ago. In fact, up until recently, he barely watched TV at all. The key here is probably that moderation factor. That we can't be so busy in our lives that we default to television as a babysitter. Easy said than done, I know.
Just my two cents, whatever that's worth.