Problem:
my apple iPhone display screen is completly black but the touchscreen is still working
Solution:
Late reponse...
I noticed the same thing yesterday night with iPhone the first version. I was browsing the photos while my wife was using/talking to someone via the bluetooth connection. When she disconnected she noticed pitch black screen, did not response to any operation, but the phone seems to be working - I redialled through my bluetooth, mute worked, charging beeped etc. I was browsing through some other site for the issue and some posted that press and hold Sleep/Wake and Home buttons. It did not respond immediately but after a few seconds pressing Sleep/Wake showed some response, rebooted after that. Hope this helps.