There is one thing that really frosts me with some iPhone apps: When they sneak advertising into an app under the pretext that it's an upgrade or as part of an upgrade.
I understand that content providers somehow have to pay for their content. Newspapers are closing left and right, magazines are struggling, and no one quite knows how to make money by taking the content online. I really understand that. But please be honest about it! Simply sneaking an obnoxious ad feature into an app as part of an "upgrade" is just not right. Announce it, give people an option, but don't make them "upgrade" to an app that'll then be polluted with ads without first telling them!
The practice of retrofitting ads into a free app is objectionable enough, but it gets downright vile when I pay for an app which is then "upgraded" to one that nags me with ads.
And if we must have ads, and again, I understand that there cannot be truly free content, let's not cripple apps in the process. It's underhanded to make ads pop up in a place where people usually touch to scroll in an attempt to hawk a few more (inadvertent) clicks on an add. It also backfires when adds and toolbars are beginning to take up a large part of the iPhone's precious real estate. Yes, I remember offenders and my view of them will take a hit, quite the opposite of what they had in mind.
Since Apple is so meticulous and concerned about the look and quality of approved apps, perhaps they should create some guidelines on how ad-supported apps must be described and where ads can be.