Where is the boundary beyond which the link-building is considered black hat? I remember in the past black hat was referring mostly to deceptive tactics like invisible links, serving different page to Google and to humans for the same URL, etc.
Thanks; I get to work with a wonderful/smart group of people at Google--they're doing the really hard work. Both webspam and search quality folks are crunching on linkspam and content farms, so I hope we'll have more to talk when some of the things in the pipeline make into production.
