With services like del.icio.us, Twitter, Pownce, Tumblr, FriendFeed, etc. there has been a rise in something that I consider highly insidious – cross posting. Cross posting is the exact opposite of post aggregation and should be discouraged and, in my opinion, treated as spam.

1. It increases noise. I’m following you only on Twitter for a reason. It’s not so I can get pinged every time you post something new to one of the 30 social sites you’re on. It’s so I can get your thoughts, musings and annoyances in little 140 character pieces throughout the day.
2. It hurts usability. Not only do I have to log in and take action on Twitter or del.icio.us, but I also have to go and log into Pownce or Facebook to see what you really posted.

I’ve unfollowed people that actively practice this (including a good friend whom I’ll leave nameless). I don’t have any problems with posting the same thing to two different networks. Just don’t automate it and don’t make me jump through hoops to get to the end result. 

UPDATE: I also hate it when people automatically tell me where they are on Twitter via the billion different location services. If I really care to stalk you I’ll follow you on Brightkite, Dodgeball, etc. 

UPDATE: Updating your Facebook feed with your Twitter status isn’t too bad with the exception that it still kind of messes up usability since my Facebook friends probably have no idea who @a is.