I know a lot of B2B marketers are experimenting with social networking sites -- I've been getting added to people's Facebook accounts at a rate of dozens per day -- but there is one nefarious site you should avoid right now: Quechup.
Apparently, in an attempt to spread itself virally, Quechup, a new social network, is taking advantage of users uploading their contact lists and inviting people in your email address book without your consent. This is a violation of the number one governing principle of social networks: trust.
Read more about this and what you can do about it in Matt Dickman's Techno//Marketer blog.
Update: Dwight Silverman of the Houston Chronicle has more on this story.