Well, as of today, I have put in 3,543 miles and 223 hours of riding for 2007. That's 343 more miles than last year. I didn't reach my goal of 4800-5000 miles due to being off the bike for 8 weeks due to the knee injury.
So, guess I will set a new goal for next year: 5000+ miles, which means I need to do at least 416 miles a month. Most likely, I will do more than that - hope to do around 600 miles per month barring injury or other things that will hinder getting those mileages.
I've had a friend tell me that measurement of miles ridden in the year is not that great of a metric. One should, if they are using a PowerTap, should measure the amount of work done. So, this year, I will still keep track of miles, but will also monitor the work (kJ) I do on a monthly basis..