Well, the GG has exercised her prerogative, and even though I don't agree with her decision, I can see the merits of the arguments on both sides - hence why this was such a tricky decision to begin with, as the arguments of both sides certainly did have merits.
But this just gives the coalition another month to firm up its commitment to topple Harper, in much the same way as Harper delaying the confidence vote a week gave the coalition time to hammer out some more specifics. The coalition would be wise to use this time to come up with some common policy proposals, maybe even a proposed throne speech, so that it can be ready to govern the day it defeats this shameless coward of a prime minister.
While anti-constitutionalism is nothing new from either Harper or from conservatives in general, it should give the coalition further resolve to defeat this dangerous man and his cabal. They clearly have no respect for the constitution of Canada, or for the principles of responsible government on which it is based. This banana-republic prorogation alone is reason enough for Parliament to refuse to grant its confidence to this government, no matter what is in the much-vaunted January budget. (If it's anything like that farce of an economic update, it shouldn't be terribly difficult to vote against, anyway.)
My advice to the coalition: Use this time to hammer out a Throne Speech and a Cabinet. And for crying out loud, dump Dion! Precisely nobody except his most diehard supporters (the few who remain) want him to become prime minister; if this coalition is to have any credibility, a replacement needs to be found, and soon. If Dion refuses to step down himself, for the good of both the party and the coalition, the caucus should step in and put him out of his misery. Paul Martin had the class to resign as leader when it was clear Canadians had rejected him; Dion's attempts to cling to power, whatever you think of him (and I have nothing against him per se), are terrible optics, and if this coalition is to have any chance of success, it needs a leader that Canadians like and trust - and that is not Stephane Dion.