(All things considered, I will keep my comments to unjailbroken iPhones since those still have Apple controlled firmware.)
@ andywar
James' car analogy still holds true (replacing rims). His argument is that Honda doesn't control what he puts on his car. Granted, he prob won't get warranty service for his brakes or suspension but Honda will still service his car. Honda cannot prevent you from replacing your tires or rims...
But, this article is arguing that Apple is preventing installation of unauthorized apps. And back to the car analogy, it's like saying Honda will go out of their way just to prevent you from changing your rims or even as simple as replacing the stock headlamps' bulbs to a higher-wattage bulb.
I understand that Apple is trying to ensure that all their users receive the same level of service with their iPhones, in regards to apps, but their tightening grip is what frustrates a small portion of iPhone users. By me saying small portion, I mean a generally small group of iPhone users want to install those unauthorized apps legally and an even smaller group will jailbreak their phones. All things considered, if you didn't jailbreak your phone, you will be concerned about this, too.
Jailbreaking is like voiding your warranty for your car and going to a outside repair shop for future maintenance and repairs. The reason why people do not jailbreak their phones is that if anything does go wrong with their phones, Apple is more than willing to assist you in either fixing it or getting you a replacement, and if they their phone's firmware tweaks because of jailbreaking, that's like bringing in a heavily modified car back to the dealer and wanting warranty work...ain't gonna happen...
Of course I'm just rambling so, you get the picture of what I'm trying to say...
Don't Be Fooled, It Isn't a Walled Garden Its a Prison