I'm in Sacramento, CA as well as have to drive through Davis to get to where my folks live in Davis. I too have noticed the sheer amount of stickers reduce and have seen more of the W in 04 stickers out and about. I will also say though that I seem to be having this strange compulsion(so far supressed) to flip off the people in Davis in their 30 year old vans with and their hippies beads hanging from the mirros with the Kerry stickers. Yikes.
I live in the general vicinity of Berkeley (well, 20 miles outside it), but drive on 24 from Concord to Oakland daily. I love bumper sticker watching. Couple of days ago, I saw a Tempo or something with a HILLARY bumper sticker on it. I pulled up to check out the driver, and it was a blonde Janet Reno relative. Ick.
The best one was the HUGE Toyota LandCruiser driven by two feminists - Mutt & Jeff, one about 6'2" and the other a little Billie Jean King clone. This was at a restaurant in Concord, with a sticker that had "W" with the international slash sign through it. The irony was delicious - those EEEEEVIL gas-guzzling SUVs!
I have my W'04 sticker, and if it is defaced, I have 5 more ready to step in for their wounded brother in arms. :-)