The Montreal Expos were a baseball team from 1969-2004 before morphing into the Washington Nationals following the 2004 season. The memory of the Expos carries on, though, and the NHL's Canadiens have a banner in their honor.
Those would be the retired Expos numbers of Gary Carter, Rusty Staub, Andre Dawson and Tim Raines.
Nice touch, Canadiens.
Addendum: Yes, I realize it hasn't just been recently raised. I'm just passing along the photo of the banner.