Here's a great article on stats on how Facebook mobile is dominating its competiton:

http://www.allfacebook.com/facebook-mobile-dominates-2010-10?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+allfacebook+(Facebook+Blog)

Note the stats on apps.
And it's not just about Facebook development:

Know that Copeland Casati Media offers app development to put  your business in front of and interacting with your customers in their preferred method of connecting to you.