If you absolutely need to debug something on the device in iOS 5, I wrote this a few weeks ago: https://github.com/brainlock/ios-remote-inspector

I had a rendering bug that only happened on the device, not in the simulator.

This opens the web inspector locally, and exposes a proxy on port 55555 for you to access from your working machine.

Not really useful on iOS 6 anymore :-) but still, useful on iOS 5.