With so much up in the air with the Canadian election, it would be foolish to speculate about its impact on Canadian foreign policy. So, let me speculate away. While some have wondered about Afghanistan and Libya, the most obvious and most certain impact will be felt when it comes to defense procurement.
The F-35 is already in big trouble because the Harper government and the Department of National Defence have been far more optimistic than the Pentagon about what it will cost to buy and operate the new planes. That is usually hard to do--to provide estimates lower than the Pentagon and the defense contractors. If Harper wins a majority or minority, the F-35 will proceed. If an NDP/Liberal coalition comes into power, the F-35 will join canceled helicopter programs of the past (yes, there is no contract yet, but the plane is certainly planned, so being unplanned is close enough to being canceled for this one observer. Blame http://twitter.com/pmlagasse for this "clarification"). Neither the Liberals nor the NDP are big fans of the plane, and this is the starkest difference between them and the Conservatives and the clearest commonality between the two parties.
Afghanistan? Not so clear. The Liberals were the ones who initially proposed a training mission to replace the combat mission. The NDP have been opposed to the entire Afghanistan project. If a coalition forms, this will be a key point of difference that will need to be finessed. My guess is that the NDP would settle for the currently planned training mission since it will NOT involve combat but will have steep caveats to prevent Canadian troops from being put at much risk. If the NDP gets into power, it will feel significant pressure to be a responsible NATO member, which means that cutting and running is not so likely. Of course, one compromise would be to put a stricter time limit on the training mission--2012 or 2013 rather than 2014.
Libya? I doubt that much will change here. The mission is actually pretty uncontroversial with no casualties, few risks, and a Canadian serving as the operational leader. Plus it is the most R2P-ish thing that the Canadian Forces will be doing in the near future (unless one counts Afghanistan, which no one does).
A Liberal/NDP coalition might still be Arctic obsessed, but would spend fewer $$ on planes and ships once they find that there are significant budget constraints facing them.
The rest of the foreign policy menu has mostly been ignored in the campaign (at least by me), so I will be less foolish and not speculate so much about trade or climate change agreements.
To be clear, there will be both more and less change with a new government than folks suggest.