"The use of emerging social media (Twitter, Facebook, and blogs) by the airline industry continues to grow healthily. These venues offer airlines the opportunity to communicate with customers in a way that is much more personalized, immediate, and trend-aware than traditional advertising, PR, and customer service venues."

Project writer "Ex-United" created an overview in  this great article with data on twitter followers, facebook friends and blog google results.

How did JetBlue obtain 1 million + followers?  The table clearly shows not all airlines have put marketing (?) money in social media presence,  despite the opportunities.