I'm currently chomping my way through the QueryShark archives, and finding them extremely instructive, as well as inspiring; thinking in terms of the query has helped me sort out some plot issues in one of my manuscripts.
I'm not yet ready to query any of my own stuff, as it's all still at various stages in the process (write, incubate, revise, beta read, revise, existential crisis, revise, heavy drinking, revise, and so on), but I'm curious about something.
November is National Novel Writing Month. As an agent, would seeing in the query that a novel originated with NaNoWriMo be interesting, or is it a turn-off?
I don't want to know much of anything about how you dreamed up or wrote your novel. This is one of the things that the phrase "TMI" was coined for. Like making sausages, or writing cover copy: the less I see of the process, the better.
That said, if your novel did start as a NoNoWriMo endeavor, it will be of interest to readers and thus you'll consult with your agent about how to mention this in the pitch letter s/he sends to editors.
The very real problem with NaNoWriMo novels is not that you query them, but that you query too soon.
You may have finished writing your novel on 11/30/12 but that does not mean you're done. Not at all.