If you search that topic, it has already been suggested but they do not ever plan on it for several reasons. I'll let them explain, or see the other posts. I would be greatly appreciated, but I understand their reasons too. In the meantime take a look at http://sourceforge.net/projects/go-syncml/
I got this working somewhat with Sunbird/lightning, but not outlook or our Nokia Phones. Still needs some work and the developers seem to be at a stand still. Unfortunately I have no skills to help them with it. But the calendar at least syncs one way, sometimes two way (to my Sunbird/Lightning installation). Address book still seems not to be working all the way.