Very bad news. Apple has put some major restrictions on apps that if you don't follow they wont approve. These where take from the iPhones Human Interface Guidelines Doc
"Only one iPhone application can run at a time, and third-party applications never run in the background. This means that when users switch to another application, answer the phone, or check their email, the application they were using quits. (p. 16)" WTF
"An Application may write data on a device only to the Application's designated container area, except as otherwise specified by Apple."
"Applications may only use Published APIs in the manner prescribed by Apple and must not use or call any unpublished or private APIs."
"Applications must comply with the Human Interface Guidelines and other Documentation provided by Apple."
The full iPhones Human Interface Guidelines Doc can be view at the bottom of this page:
http://www.techcrunch.com/2008/03/07...s-arent-great/