How much does it cost to develop a mobile app on iPhone, Android and other platforms?

An interesting blog post on the subject here:

http://goldengekko.blogspot.com/2010/09/what-are-costs-of-developing-mobile-app.html

NB. The numbers are pretty accurate in my opinion.

Update: Also of interest are some of the comments in this stackoverflow question. Some frank estimates of time by some of the developers for well known apps such as twitterific.

http://stackoverflow.com/questions/209170/how-much-does-it-cost-to-develop-an-iphone-application/3926493#3926493