I peeked in on the Minnesota DNR EagleCam yesterday and managed to catch one of the parents feeding the runt of the three chicks:
A rain drop partially blurs the oldest and biggest of the three, with the next largest behind it. The small one hatched a week behind the first, but the parents have been diligent in giving it as much food as it can handle so it continues to thrive for now. The danger to it mainly lies in its siblings becoming increasingly aggressive as they instinctively train for the real world. There's more at the FAQ and some cool info on the mom's history from the band that they have been able to view on her leg.
On another note, a useful and humorous guide if you happen to find a baby songbird out of its nest.