Richard was invited to offer an opinion on +Matt Cutts
statement on guest posting - take a look at +Graham Charlton
's write up here.
Our bottom line: Bad sites that host low quality guest posts are already being detected by Penguin and often appear as highlights in failed reconsideration requests. As are link networks, heavily machine generated and programmatically distributed content sites, directory links, and so on. Given the unchanged statement in Google’s Webmaster Guidelines: “Large-scale article marketing or guest posting campaigns with keyword-rich anchor text links” I think Matt’s statement is one simply born of frustration with the lower quality tactics and that “high quality” Guest posting, regular columns, high profile features and the like are perfectly valid link building tactics.
There’s nothing new here, just don’t let your agency build crappy links to your website!