yes actually there is...
http://forum.xda-developers.com/showthread.php?t=609913
You can check out the thread at XDA. It is called "Shake to Send". The thread basically died because of lack of interest. I was very interested. The only problem - no one buys Windows Mobile phones anymore so I didn't have any one to try it out with.
If you try it and test it with some friends let me know how it works or if it still works. I gather that the app used a server and since the thread is pretty much dead perhaps the server is no longer available. The download link still works bc I just tried.