I don't think I've had to write OR even type it yet. Apart from when wishing people a 'happy 2009.' I do remember in school though that I'd make the mistake of writing the previous year a few times before I got adjusted. Thats when we had to write the date at the top of our work every day.
I've messed it up a few times already, but I think I got most of that out of my system now. I'm sure I'll still write the wrong year a couple more times though at some random moment far down the road when my mind is elsewhere. I can be a bit scatterbrained at times.