Not much, but it's a start. I confess that I already had the prologue and chapter one already written (months and months ago), but I jettisoned them and started over! I've now rewritten the prologue, and you can read it on my NaNo profile. The site's really slow right now, though.
I'm pleased with the quality of my writing so far. Each time I do NaNo I try and concentrate on some new aspect of writing or the process of writing. In 2005 I experimented with outlining, and it worked so well I've continued to outline ever since. In 2006 I tried various methods of increasing my writing output, in particular dictating my novel during my commute; that worked, but the results weren't all that impressive. This year I'm working on the quality of writing, with an emphasis on description. For years I've tried to make my prose lean and spare, but I think I've gone overboard. Time to revel in the poetry of words--without losing focus on the story or the characters.
As an example, the original version of the prologue was only 315 words long. The new version is 925 words even though it covers very little more ground than the original.
49,000 words to go. 29 days. Tomorrow I can stay up as late as I like, because it's Friday! My weekend goal: 10,000 words. I'll do it too, because I plan to reward myself with pizza.