How can I deploy an iPhone application from Xcode to a real iPhone device?

It sounds like the application isn't signed. Download ldid from Cydia and then use it like so: ldid -S /Applications/AccelerometerGraph.app/AccelerometerGraph

Also be sure that the binary is marked as executable: chmod +x /Applications/AccelerometerGraph.app/AccelerometerGraph

You can't, not if you are talking about applications built with the official SDK and deploying straight from xcode.

You'll have to jailbreak your device.

No, its easy to do this. In Xcode, set the Active Configuration to Release. Change the device from Simulator to Device - whatever SDK. If you want to directly export to your iPhone, connect it to your computer. Press Build and Go. If your iPhone is not connected to your computer, a message will come up saying that your iPhone is not connected.

If this applies to you: (iPhone was not connected)

Go to your projects folder and then to the build folder inside. Go to the Release-iphoneos folder and take the app inside, drag and drop on iTunes icon. When you sync your iTouch device, it will copy it to your device. It will also show up in iTunes as a application for the iPhone.

Hope this helps!

P.S.: If it says something about a certificate not being valid, just click on the project in Xcode, the little project icon in the file stack to the left, and press Apple+I, or do Get Info from the menu bar. Click on Build at the top. Under Code Signing, change Code Signing Identity - Any iPhone OS Device to be Don't Sign.

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.

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..