I have just been sent Live Earth ratings by our Nielsen guru, Rick Kissell. It shows that the concerts didn't exactly break any records.
According to Nielsen estimates, 19 million Americans watched at least some of Live Earth across all of the NBC networks, which is not bad but not especially big considering the blanket coverage and big name acts.
In primetime, NBC averaged 2.7 million viewers, finishing behind ABC (3.4 million), Fox (4.6 million) and CBS (5.2 million).
Live Earth did break some records for online hits, according to organizers. But it's interesting to note that broadcast networks have had a tough time with concert broadcasts in recent years, so the fact that Live Earth didn't do well in prime time isn't a major surprise.