iPhone OS 4 and it’s SDKs were released for the paid iPhone developers on 8, April 2010. Since then iPhone application developers have been digging into SDKs; After spotting the iChat client services earlier with front facing camera libraries, now, Facebook integration has been spotted by Gunning for Safety (which, amazingly, seems to have two areas of interest: nail guns, and iPhone OS).

According to that blog, Apple is probably working on Facebook’s Event Calendar, Contacts to integrate with Calendar, Contacts app on iPhone, respectively. Currently, iPhone has easy setup options for you to setup your accounts on Gmail, MobileMe, Yahoo, etc. You can simply type in your details and you’re done. Facebook, might get listed in this as well.

There was a huge user request received by Joe Hewitt (iPhone Application Developer of Facebook) during development of Facebook 3.0 for iPhone. So, it might be possible that on the other hand Facebook team will work on existing Facebook App to get the proper end user integration.