New with the latest seed of 10.9.3 is the return of iOS device syncing over USB! You can once again sync contacts and calendars between an iOS device and your desktop Mac without using iCloud.
As always, back up your devices (both Mac and iOS device) before testing.
Your iOS device may need to be signed out of iCloud in order to be enabled for USB syncing.
You need to be running both the latest seed build of 10.9.3 (13D21) and the special seeding version of iTunes (11.1.6b5) in order to have access to the feature. iTunes 11.1.6b5 should appear in the Mac App Store as another “Pre-Release” update option, just like 13D21.
You can use iTunes 11.1.5 normally on 13D21, and you can use iTunes 11.1.6b5 normally on earlier builds of 10.9.3 or 10.9.2, but the syncing features will not be visible or useable without both.
Because iTunes 11.1.6b5 is also pre-release, it and the USB syncing feature are subject to the same confidentiality requirements as the 10.9.3 build itself.
When reporting any issues you find with iTunes 11.1.6 or USB syncing, use iTunes as the area in which your bug occurred.