I believe the Canadians were the last Canadian team to win...beating the Caps.
They may have beat the Caps at some point in the playoffs, but it wasn't in the Cup Finals. Montreal beat the Kings to win it in 1993.
From the Pointless Back-Patting Dept: I was right above. Until now, the longest the Montreal Canadians (let alone any Canada-based team) had gone without a Stanley Cup win (since the founding of the NHL in 1917) was 12 years, from 1932-44.
And from the Useless Information Dept: The Stanley Cup has been in existence since 1893, and the Canadians did not win their first one until 1916 as members of the National Hockey Association (the team wasn't founded until 1909). But even if you want to go back that far, they're still only 2 seasons shy of the current drought.