Personally, I think that anybody with an iPhone, Blackberry or Google phone can already access all the BBC's news content via their mobile browser. Developing apps to display the content in a mobile friendly format is of benefit to the readers, and as the head of the BBC's "future media development" has said, the audience "want to access the digital services that they have paid for at a time and place that suits them".
This hits the nail right on the head. The existance or lack thereof of a BBC News app won't stop iPhone users from reading BBC News on their iPhone. Having a BBC News app would just allow them to access it in a more small-screen friendly format.
There is no common sense reason for the BBC to be kept out of this market. RTÉ has launched a free news app and when it works it works great.
The probable compromise, of course, will be for the BBC Trust to authorise an app but to stipulate if be launched by BBC Worldwide and be paid-for.