The iPad (and iPhone 4) rely on an LCD display, even as many of Apple's competitors have switched to an Active Matrix OLED screen. The advantages of my OLED screen on my Droid are in higher refresh rates and lower power consumption as compared to the TFT technology currently used by the iPad. To increase the already impressive 10 hour battery time on the iPad the AMOLED display would be a good move.
Rumor has it that Apple considered the switch for the iPad 2, but supply constraints and some quality-related issues prevent Apple from making the change. The power consumption of a TFT LCD is 2-5 times that on an OLED screen since the pixels directly emit light.