Now Up-to-Date & Contact is not capable of syncing to iPhone directly. Now X, which is currently in public beta, does sync with sync services and therefore shares data with the iPhone through Apple's sync engine.
Some people have been using the Now X public beta as an interim solution to push information to the iPhone from Now Up-to-Date & Contact, and they do this by importing their NUDC data into Now X, syncing to Sync Services, syncing their iPhone, then clearing their sync services and Now X data and repeating the process on a regular interval. Others have switched to using the Now X beta exclusively, although we don't suggest using the beta software as your production software and highly recommend backing up your data regularly when using the beta.
There is an FAQ on syncing Now X with sync services that you can read here:http://forum.nowsoftware.com/content/viewtopic.php?f=75&t=2454