I believe that last.fm works because it scrobbles what you've listened without you ever noticing. Having to manually mark an episode as "watched" is a big hassle and will never work well.
So this is a good idea, that implemented some nice features but that is not solving the main problem. Boxee solves that problem but misses these satellite features.
Your site, as far as I can tell, is _not_ free internet TV. So to most people I wouldn't call it last.fm for TV shows.
Very cool to see followmy.tv suddenly appear on hackernews.
Thanks for the feedback so far, about the scrobbler question, we are planning to integrate with a bunch of software to make it easier to "check off" episode.
Keep the feedback coming, it's highly appreciated.
One negative point though is that since I've discovered this app my tv shows I follow probably increased threefold, which at times has had its consequences regarding productivity :p