Fox News Channel was the most-watched cable news network beating out CNN and MSNBC combined in total viewers between the hours of 2 and 4 (the time between the announcement and the new Pope's first words). FNC also won the time period in the key demo (25-54) during that time period. See the numbers below for more.
2-4PM (hours when new pope was announced, when his name was announced and when he spoke):
FNC: 2.232 million viewers (443,000 in 25-54)
CNN: 1.497 million viewers (420,000 in 25-54)
HLN: 913,000 viewers (315,000 in 25-54)
MSNBC: 597,000 viewers (142,000 in 25-54)