So LinkedIn now allows you to update your status with your Twitter updates. There are already applications that help you post your Twitter updates to Facebook. And then there’s FriendFeed that allows you to consolidate all your social activity and push that on Facebook and other social media sites. Not to mention other aggregation services, RSS feeds, email alerts, etc. etc.
However, if your social network looks like the one below, you are bombarding your connections with the same update on all networks. This can be very irritating for your connections.
My rule of thumb – limit convergences of updates on different social media services irrespective of the overlaps of your connections.