So, I earlier highlighted  how Stephan reported on Matt Cutts revealing that Google treats underscores as white-space characters. Now Barry Schwartz has done a fantastic follow-up  by asking each of the search engines if they also treated underscores just like dashes and other white space characters, and they’ve verified that they’re also handling them similarly. This is another incremental paradigm shift in search engine optimization!
I’ve previously opined that classic SEO may become extinct in favor of Usability , and announcements like this fluid handling of underscores would tend to support that premise. Google, Yahoo! and MS Live Search have been actively trying to reduce barriers to indexation and ranking abilities by changes like this plus improved handling of redirection , and myriad other changes which both obviate the need for technical optimizers and reduce the ability to artificially influence rankings through technical improvements.
I continue to think that the need for SEOs may decrease until they’re perhaps no longer necessary, so natural search marketing shops will likely evolve into site-building/design studios, copy writing teams, and usability research firms. The real question would be: how soon will it happen?