Working support of SSL was just committed in libSystem [1], for remote procedure calls as provided by the AppServer/AppClient API. At the moment, it requires server certificates to be generated and placed (along with unencrypted private key) in an undocumented place, but this will be settled as soon as possible. Error management will also require a solution eventually.
On a related note, a PKI module is getting into shape in DaPortal [2], just like lots of code cleanup and minor improvements. More on this later.

[1] https://www.defora.org/index.php/project/browse/27/libSystem?file=/src
[2] https://www.defora.org/index.php/project/browse/12/DaPortal?file=/modules/pki