I think this is a good thread of discussion that helps us understand where to put the blog.
The argument is as follows:
http://www.domain.com/blog - gives best PR relevance to the entire domain
http://www.blog.domain.com - not sure what its really saying
Separate domain - better if the blog is more about having a company voice and authority on the subject.
http://forums.searchenginewatch.com/sho ... ge=2&pp=20