I already have more online commitments than I can keep up with comfortably, so comments to the Twitter feed go mostly unread and unanswered. It's tough enough keeping up with comments on what I actually write, on this and other blogs. If you think you wouldn't like a book on Book View Cafe, or you are opposed to space exploration, or you disagree with the opinion of a blogger on a site somewhere--don't bother to tell me and expect a discussion. The re-tweets can take you to the original person who tweeted about that, and to the sites, and it's really at the sites that you can express yourself and hope for a response.
And now, back to the novel in progress.