Hootsuite, Tweetdeck and similar programs can post to multiple social channels. Nothing does them all as there's so many potential networks and only some expose a public API but it's a good start.
However I would strongly urge you to avoid posting the identical message across all channels. Not only is this a bad practice for your community [why would someone follow you on more than one for the same stuff] but each is so different that to go to the lowest common denominator is a major setback. Remember, social is not a broadcast medium... you need to be interacting and management tools are designed to help you do that first and foremost.