via NBC press release (I know some of this info was already posted, but the release has data on the top 10 markets).

NHL WINTER CLASSIC ON NBC DELIVERS BEST REGULAR SEASON OVERNIGHT IN NEARLY 13 YEARS

Tops Last Year’s Event by 12%

NEW YORK – January 3, 2009 – NHL Winter Classic 2009, broadcast New Year’s Day on NBC from historic Wrigley Field, earned a 2.9 overnight rating and a 6 share (1-4:15 p.m. ET), the best overnight NHL regular season rating in nearly 13 years (Feb. 3, 1996 on Fox, six-game regional, 3.0/7) and a 12 percent increase over last year’s inaugural event (2.6/5, 1-4:45 p.m. ET). The Detroit Red Wings defeated the Chicago Blackhawks 6-4 in the second U.S. outdoor game in NHL history.

“Year one was an extraordinary experience. Year two was the establishment of what promises to be a great tradition,” said NBC Sports President Ken Schanzer.

Top 10 Metered Markets:
1. Chicago 11.8/21
2. Detroit 10.5/20
3. Buffalo 10.1/20
4. St. Louis 5.3/10
5. Pittsburgh 4.4/8
6. Denver 4.2/10
7. Providence 3.5/7
8. Indianapolis 3.4/6
9. West Palm Beach 3.3/6
10. Orlando 3.2/5