Don't worry. Just because we used the words "ping" and "social" in the same headline doesn't mean we're talking about that other social network. No, this is Seesmic Ping. From the developer who brought you the original Seesmic, Seemic Ping lets users post to Twitter, Facebook, and LinkedIn with one update. You can even do it from the past!
Seesmic Ping lets you schedule tweets and status updates for future dates.