Judging by the number of catalogs and new title review inquiries I've received this year, publishers are starting to realize the benefit of book reviews on blogs. Authors should pay attention and invest some time and effort in this as well. A review of your book on some of the more popular and well-targeted blogs is likely to result in as much (if not more) interest and sales than you'd get from the typical in-store book tour/appearance/signing. And you can do it all from the comfort of home.
Here's a recent story about book blog tours in The New York Times. It closes with an interesting observation from Dave Weich, director of marketing and development at Powell's Books in Portland: "the dirty little secret of real-life author tours, he said, is that 'most of the people who go to events don’t buy books.'"
Authors, work with your editors to find out how much effort your publisher's marketing team is likely to invest in this area. You don't want to step on their toes or duplicate their efforts. Once you've determined the publisher's plans, do some research of your own. Dig around a bit with Google Blog Search, Technorati, etc., and find the most popular blogs that cover your book's topic. Send that information to your editor and let them know you plan to reach out to all the bloggers on the list to find out who might be interested in reading and reviewing your book. I also suggest you ask your editor for enough additional comp copies of your book (beyond the quantity in your contract) to cover the ones you plan to send out; it's the least your publisher can do since you're offering to establish contact with these bloggers and mail everything out. Finally, follow-up on all of this. Check back in with the bloggers to make sure they got their copy and if they plan to read/review your book. Also, ask them to post their reviews on the various online book sites -- it's usually a simple cut-and-paste effort and takes no more than 2 or 3 minutes.
(Thanks to former colleague Juliana Aldous for flagging this article on her publishing blog.)