A beautiful infographic prepared by GigaOM outlines the size of the iPhone App economy. Go check it out. We'll wait.
$250 million revenue in December 2009
$175 million (70%) goes to developers
$75 million (30%) goes to Apple
Apple sold 8.7 million iPhones in Q4 2009 (not counting Touch)
Guessing $150 / phone, that's $1.3 billion, plus carrier subsidies
Users spend an average of $4.37 per month on apps
Users spend (my guess) $80 per month on connectivity
App Development is Big.
iPhone sales are Bigger.
Data plans are Biggest.