From
http://www.mlive.com/wolverines/other/index.ssf/2009/03/wisconsin
_formally_announces_i.html
"The University of Wisconsin made it official on Friday: The
Badgers will host Michigan in an outdoor hockey game at their
football stadium next Feb. 6 in a showcase dubbed the Camp
Randall Hockey Classic.
The venue's 80,321-fan capacity means the game could surpass the
Michigan-Michigan State game at Spartan Stadium in 2001 that set
a world record for outdoor hockey attendance at 74,544 fans.
Wisconsin also said its women's hockey team will play Bemidji
State after the men's game."
The article also mentions another outdoor game between Michigan
and Michigan State during the 2010-2011 season.
Rest of article at link above.