I mess around on the piano, which I bought this last year. Love it to death, it's great to just play when you need a break. (BTW I cannot recommend the Yamaha GT2 enough). I'm absolutely terrible at reading music, but I can play anything by ear, I wonder if that's usual for hacker types. http://uk.youtube.com/watch?v=y6UPJJqwc1k
I think it has more to do with how you learned the instrument. Most classically trained pianists I know couldn't sound out a Doors tune to save their life. On the other hand, once I started playing in bands, just about everybody I met could listen to a song and have it figured out within an hour.
I (a hacker type) was better than most classically trained types at sounding out music, but still had difficulties compared to most people in the band circuit. I usually couldn't really nail a part unless I found the music in a magazine somewhere. (this was pre-Internet, today this wouldn't be an issue)