Efficasoft Mobile Express: Manage your SMS's for free!
Ricardo Chaves over at PocketPT.net as called to my attention on this free application from Eficasoft that allows one to manage their SMS's stored on a Windows Mobile Device via an Activesync connection.
Not only can you manage your SMS folders as you are able to export them and create and send new SMS's.
There is another software that has similar functions and integrates with Outlook, however it is commercial: Jeyo Mobile Extender 2.5.
You can download this great application here, for free.