Apple is looking to integrate social networking data from Facebook into its iPhone operating system software, as a wide range of clues have been pointing to over the last couple of months. Now we have another one.

The site Patently Apple has found a patent that the company filed in late 2008, and published recently, describing a range of integrations for syncing with social networks. While the processes could fit with any number of services, the patent uses Facebook as the main example.

It shows workflows where an iPhone user could ask to friend a Facebook user from their device (presumably straight from their phone address book), or sync existing contact information, calendars, photos, notes, app-specific data and other custom scripts.

Other phones have already offered many of these sorts features, but Apple and Facebook provide the best-of-breed features in their respective categories. This is illustrated by the Facebook iPhone OS app — it’s been a hit for years. With 34 million monthly active users and around half that using the app every day, it’s currently one of the most popular on either company’s platform

Look for Apple to reveal more at its June 7 iPhone OS 4.0 launch event.