Using a MEGA2560, updated libraries and Arduino IDE 1.0... here is what I did:
I copied the code from your post (1st one) and installed a DS1820 on a breadboard. Installed 4.7K to signal pin from 5V. Powered the sensor from 5V (no parasitic). Used the same pins. Uploaded your code unchanged and opened serial monitor.
Results:
Locating devices...Found 1 devices.
Parasite power is: OFF
Found device 0 with address: 10F0C32500000014
Setting resolution to 9
Resolution actually set to: 9
Requesting temperatures...DONE
Temperature for device: 0
Temp C: 23.76 Temp F: 74.77
Requesting temperatures...DONE
Temperature for device: 0
Temp C: 23.75 Temp F: 74.75
So it's hard to blame the code from my perspective.