laravel/laravel — pull request #1424 by lavaeagle (2012-11-06 16:08:22+00:00)
Title: added $attributes to sync() like attach()

sync is basically a shortcut to a foreach loop using attach. Now you can pass attributes you want synced as well since it's just using attach() anyways.
I use this personally for attaching user_ids and some other parent user ids for project management so I know exactly who owns what.