
UPDATE: People have asked some questions about this, so I'll answer them here. (Too long for Twitter.)
What is NaNoWriMo? It's a challenge to write a novel of 50,000 words (or more if you want) in one month. You can read more about it here.
Are you going to post your novel online? I have no plans to do that.
What is your novel about? I wanted to do NaNoWriMo this year, but I had forgotten all about it, what with having a baby and all. Then I saw someone mention it ten days in. I didn't want to miss it, and 2500 words a day seemed doable, so I joined in. I didn't have an outline nor any other support material, and I didn't have time to develop any, so I treated the term "novel" pretty loosely. (Yes, this is allowed.)
The novel has a single thread of dialogue that runs throughout about writing; writing under pressure, analyzing writing, joking about writing, overcoming the inner editor in writing, etc.; and interspersed with this dialogue are bits of fiction. Some of them stand alone. Others are continuing stories that are revisited over and over. A few are even exercises from John Gardner's The Art of Fiction
Overall, I think it would be very enjoyable for me to go back and read, and to steal story bits from to develop into other things, but I don't know that it would be of interest to anyone else. None of this is to say that it isn't a novel. It is, and it's about the mind of the writer.
So if you aren't going to post it, and it's weird, what was the purpose of writing it? To develop as a writer. To prove to myself that I really can sit down in a disciplined way each day and churn out mountains of prose if I decide to do it. For me, that's huge. Also, it allowed me to explore a lot of different ideas and methods. Perhaps most importantly, it killed my tendency to be a fiction perfectionist on a first draft. That's incredibly freeing.
If you are a writer, I recommend doing NaNoWriMo without reservation. It's sort of like having a writing retreat without leaving the house. It also allows you to take at look at how your writing skills have developed. If you have an otherwise busy life, you'll have to write so quickly during NaNoWriMo that you'll be relying on habits and skills that you have already mastered. If your skill at doing a certain type of writing needs work, NaNoWriMo will uncover it because you'll find yourself stuttering along or floundering when that skill is required.
If you don't have a family or a demanding job, and you have a lot of writing experience, I would recommend shooting for a higher word count. I'm not sure that NaNoWriMo works the same way if you have plenty of time on your hands. I think you need to feel squeezed to get the benefits I listed above.
I am definitely planning to do this next year. If you want a similar group writing challenge and don't want to wait a whole year, you might look into Script Frenzy. I'll probably join you.
Good luck!