In no particular order:

Fall of the Liberals: They entered the decade with a strong majority and suffered major losses in every election since

NDP: They entered the decade on life support and came back

Sovereignty in Quebec: Declined as a relevant issue, as "sovereignty fatigue" drove the PQ out of office in 2003 and was responsible for the rise of the ADQ in 2007. In 2008, the PQ would for the first time in its history improve its seat count without soverignty being front and centre

Minority Crisis: The election of a minority in 2004 rocked Parliament, as the governing parties had up until now been used to having total control. With one-seat margins between 2004 and 2006, floor-crossings and independent MPs suddenly became more influential and the upheaval proved difficult

Coalition Crisis: In 2008, the Opposition was prepared to take out the governing party and replace it with a coalition. Like the above, this rocked Parliament as moves like this had been rare in Canadian politics.

Nova Scotia: The first province east of Ontario to elect an NDP government.

Manitoba: The NDP wins historically large majorities, thus becoming cemented in Manitoba politics

Saskatchewan: The Saskatchewan Party sends the NDP to its lowest ever popular vote since the 30s, ending not only the party's 16-year reign but throwing the future of the NDP in doubt

BC: Gordon Campbell's Liberals reduce the NDP to 2 seats, a setback from which the NDP still has yet to recover.

Who cares anyways?: Federally and in many provinces, average election turnouts decline, setting new record lows in many cases