First airline to replace 25 lb. flight manual with iPad and 400 MB PDF of manual. 3/4 of 1,400 total pilots have them, but only using on ground and above 10K feet.

"Right now at Alaska Airlines, the Federal Aviation Administration has approved using the iPad for viewing manuals in flight. Pilots are also allowed to download weather map information, not normally available on paper, while they are still on the ground. But while all of the maps and navigational information is available for the iPad, the FAA is still evaluating whether it trusts the iPad enough to allow pilots to rely on that that information. 'They want to make sure this electronic "paper" is always going to be available, so you have backups," said Freeman.'"

See links:
http://www.king5.com/news/local/Alaska-Airlines-pilots-using-iPads-in-cockpit-122475984.html
http://www.geekwire.com/2011/goodbye-paper-flight-manuals-alaska-airlines-outfit-pilots-ipads