So, I've spent about a month trying to be a part of the Kindle Board community. My conclusion: For me, it's not a good use of my time. Here are my reasons:
1) You can't talk about your books in the reading forums. So all the owners of Kindles asking for book recommendations, you can't recommend your book. Okay, that's kind of expected. But if someone asks a question about the appeal of self-publishing, you can't chime in about your experience. If someone asks why anyone would write about aliens, you can't share your opinion of why you would/want to/did. You are not supposed to let on that you're a writer at all.
So where can you talk about your book and you as a writer? In the writing forums.
Which leads to number 2:
2) The writing forums are full of authors trying to sell their books to authors. I have yet to see a single post from a reader in there.
But still, many of the authors are quite supportive. Of self-publishing. They encourage each other, they respond, they spread the word. They feel a sense of unity, of pride in bucking the trend of traditional publishing.
I'm not self-published.
And so, 3) If you are not what they consider "indie published" (never mind that Indie actually refers to independent presses, not self-publishing), they don't consider you a part of their group. No matter what I post about, how I try to contribute, my posts aren't responded to. Perhaps many of them feel that they've been snubbed by traditional publishing, and therefore this is their opportunity to tell traditional publishing where to go.
I haven't figured out where that is just yet, but anyway.
If you are self-published, you need to be on these boards. If you're not, it can't hurt to announce yourself and see what happens. But I wouldn't devote a lot of time to it.
Just my 2 cents.