Do you think you need an iPhone app? It is very well could be that you do and we, at Leaping Bytes, will be more than happy to help you with creating killer application. However, it is equally possible that what you really need is a smart phone optimized web application - and, if this is the case, Leaping Bytes will be able to help as well. We are "fluent" with Cocoa Touch and Sencha and we do know when to use one or another.
Our Apps Development Toolbox: Sencha Touch, Cocoa Touch, Objective-C, jQuery Mobile.