How can I deploy an iPhone application from Xcode to real iPhone device without having a US$99 Apple certificate?
Solution posted by Cawas works perfectly with XCode4, too. However, there are some changes to IDE's UI, so you need to make some research to find Run Script :)
In the Project Navigator view click the root item of the project, then in the middle window select Target, then click Build Phases tab and at the bottom you'll see Add Build Phase button, click and select Add Run Script, then paste "codesign" script posted by Cawas.
You'll have to jailbreak your device.
I was going through the Apple Developer last night and there in the Provisioning Certificate I found something like - "Signing Team Members". I think there is a way to add team members to the paid profile. You can just ask to the App Id Owner(paid one) to add you as a team member. I am not sure. Still searching on that.
Nothing I've seen anywhere indicates you can ad-hoc deploy to a real iPhone without a (paid for) certificate.
You can't, not if you are talking about applications built with the official SDK and deploying straight from xcode.
There is no workaround. You can only ad hoc deploy apps if they are registered with your device. This prevents you from building your own app store..