Stock 1.6 and Cyanogenmod 5.0.8. Regardless of the firmware, the phone is slow as molasses. Things like going back to the home screen after texting takes 6 seconds +. Opening the dialer app takes 4 seconds, when typing, I seem to be able to type so much faster than it can keep up with and text turns into a mess. I'm not sure if this is the firmware, or the phone is just slow. I'm considering picking up an iPhone 3G as at least my dad's can do something without wanting to throw it at a brick wall.