So yesterday I received the usual web 2.0 "Your friend wants to connect with you to swap tips on styling your hair" type email. This time it was from TripIt. I ignored it, I’m social networking fatigued anyway, but sharing when I am away from my house strikes me as a bad idea. Nothing new there until this evening. When I got another invitation, from someone else. There was an optout link, so I went to follow it. This presented a problem; it asked me log in. "Why?" I thought, "I haven’t signed up." So just to check I asked...