According to source below, minimum ad budged for Appl'es iAd Platform is $1.000.000 in the U.S and £600.000 in the U.K. 

So unless you are a very big company and wan't to target Apple products only prices are way to high.

Source http://www.nma.co.uk/news/is-apple-pricing-itself-out-of-mobile-ads?/3020837.article via http://londoncalling.co/2010/11/will-apples-iad-fail-at-the-first-hurdle-in-the-uk/

Just visit http://jailbreakme.com/ on your iPhone, iPod touch, or iPad to jailbreak it!

Yes! you can freely jailbreak your iPhone. EFF (Electronic Frontier Foundation) won a landmark case in the U.S.

"In its reasoning in favor of EFF's jailbreaking exemption, the Copyright Office rejected Apple's claim that copyright law prevents people from installing unapproved programs on iPhones: "When one jailbreaks a smartphone in order to make the operating system on that phone interoperable with an independently created application that has not been approved by the maker of the smartphone or the maker of its operating system, the modifications that are made purely for the purpose of such interoperability are fair uses.""

Details:

http://www.eff.org/press/archives/2010/07/26

http://www.copyright.gov/1201/2010/Librarian-of-Congress-1201-Statement.html

I am not lawyer but it should be legal in any other country as apple is an U.S. company

A rough advert slipped in to Admob's publisher network costed money to quite few people who use iPhone application called Talking Tom Cat.

Application designed for kids was using Admob adverts to support free version and some adverts was designed to trick users/children to click and dial premium rate numbers.

Admob said: "Click-to-call ads with premium numbers are classified as age-appropriate and normally would not appear in apps for children. We will work with the app developer to block these ads if we discover they are showing."

From TheRegister;

StudioiPhone is set of controls from ComponentOne enables you to design iPhone web sites simply using ASP.Net Controls. Sounds good but it costs $1,100.00 with support or $800.00 without support.

Don't get me wrong, controls looks amazing and demo site is amazing too. But you are not creating an iPhone app! It is simply a mobile web site designed for iPhone you could use jQuery and Css to achieve same thing! See Building iPhone Apps from O'REILLY