Do Dashes in Domain names hurt SEO ranking?

[JoshKimber]

I have found conflicting reports online whether or not dashes in domain names hurt/help ranking.  Example yourbrandonline.com vs your-brand-online.com?

I found Rand's write up on how to select a domain and he suggests staying away from hyphens but mainly because its hard to remember or people my enter it in wrong.  Here's his comment.

"Reject Hyphens and Numbers
Both hyphens and numbers make it hard to give your domain name verbally and falls down on being easy to remember or type. I'd suggest not using spelled-out or roman numerals in domains, as both can be confusing and mistaken for the other."

Aside from people possibly struggling to get there directly because of the domain name, are they OK to use?  Or, are domains with hyphens considered spammy?

Thanks in advance.

[MikeRoberts]

Spammy domains have been known to overuse the Hyphen... but using Hyphens does not make you spammy

Matt Cutts had previously stated that Google recognizes the Hyphen as a separator and the Underscore as a connector... i.e. "red-wigdets" gets read as "red widgets" while "red_widgets" gets read as "redwidgets". For keyword purposes, a hyphen is technically better but the difference is likely negligible. Also keep in mind the EMD update. If your core term is "cheap red widgets" and your domain URL features "cheap-red-widgets" then the EMD has made the previous positive name correlation into a less powerful signal.

Matt Cutts 2011 Underscore vs Dashes in URLs video http://youtu.be/AQcSFsQyct8

Matt Cutts 2009 Underscores or Hyphens in URLs video http://youtu.be/Q3SFVfDIS5k

Matt Cutts 2005 Dashes vs. Underscores blog post http://www.mattcutts.com/blog/dashes-vs-underscores/