An article at E-Commerce Times talks about a recently-filed lawsuit against Boston.com, a NYTimes company, that is being sued for its linking practices. According to the article, the simple presence of a link has prompted the suit, but from CenterNetworks, the real reason might be apparent: GateHouse, the company suing the Times, is upset because Boston.com is linking to subpages of the site, thereby causing readers to bypass the significant advertising on GateHouse's home page.
(My commentary: If there were no links there at all, GateHouse still wouldn't see traffic to its homepage. Be happy that you got the link!)
In any event, there is some worry if merely linking will require permission in the future. That would be a pretty silly move.
Then again, I worry that the E-Commerce Times article that WebmasterWorld members referred to isn't accurate since every other article I read on the subject matter is about circumventing the advertising.
Forum discussion continues at WebmasterWorld.