From Mike Dover at Wikinomics blog:
A lot of people run into these etiquette errors as they are getting used to a new social network. I have a presentation that I’ve delivered several times (often for fifty bucks and bus fare) where I describe LinkedIn as a Grey Flannel Suit and Facebook as a Hawaiian Shirt. It’s good to have both in your wardrobe, but if you show up at a board meeting in a Hawaiian Shirt you look like a goof and if you show up on a boathouse roof in a Grey Flannel Suit you look like an ass.
via Wikinomics» Blog Archive » Grey Flannel Suit vs. the Hawaiian Shirt.