Breadcrumbs won't help a site answer users' questions or fix a hopelessly confused information architecture. All that breadcrumbs do is make it easier for users to move around the site, assuming its content and overall structure make sense. That's sufficient contribution for something that takes up only one line in the design.
After reading this article over at Yahoo Technology I began to remember some "experiments" at previous search conferences. Then I began to wonder how soon someone would turn an "experiment" into reality and really start being evil.