I would like an iphone app developed that allows IM between two iphones. Offline messages are a must an should support push notification. I would imagine this will require a iphone app and maybe some code that runs on a webserver to handle message delivery. But I am open to suggestions on the architecture. This is a tool for an internal team so it doesnt have to be pretty.
A user should see a list of people they can chat with.
A user should have a screen of all current chats.
An example of a mature product would be whatsapp messenger.
At first the app only needs to send txt but in future projects I will want to transfer video, pictures, location, and contacts.