Well, that was productive...NOT!
Turns out, our friendly tax assessor deemed our house "not 100% complete" when he drove by on 1/1/07, so our house was "not 100% assessed in taxes."
That's governmentese for "you got a break last year on paying your taxes lady, and be lucky we can't retroactively go back and get more money from you!"
This year, on 1/1/08, the assessor deemed our house 100% complete, so we were "fully assessed" - which resulted in a 45% (or so) raise in our MAV (maximum assessed value). How did they work that magic? :) See, Oregon has a law that property taxes can only raise 3% per year - but there are "Property Event Exceptions" (read: loopholes) that allow counties to do stuff like what they did to us.
If it is any consolation, from this year on we'll only see 3% per year. Unfortunately, now our mortgage payment will change (read: go up).
Sigh. Can't win - and I feel extremely lucky that there is no legal way they can get what they consider "back taxes" for the year they assessed as not complete.