calDav todo sync

I have set up support for caldav on my web server and can sync using SOGo caldav server from various devices etc. What seems to be missing is the ability to synchronize my todo events onto the iphone via caldav. Does anyone know if any software exists to do this 'pardon the pun' or is this something apple
is likely to announce soon?

I mean it works on the iCal desktop version so why not on the iPhone/iPod Touch?