I'm not sure if this is what you had in mind, but someone asked a related question awhile back and I posted some info about an iPhone app (My Songbook) which is available through the iTunes App store. This iPhone app support files which use the Cordpro format which is also used here on Cordie. Here's the link to that thread for more info....
This app doesn't sync files directly from your PC to the iPhone, but it does provide a few different ways of transferring files from your PC to the iPhone via your webmail account or if you have a website where you can upload/store files. You can also access Cordie.com from within the app and download songs directly from here.
Taylor 314CE, Ovation Elite L718, Cortez 12-string acoustic, Fender Stratocaster, Kala Makala MK-T Uke
Fender Champion 20 Amp, Acoustic AG15 Amp
Line 6 Relay G10 Wireless Guitar System