Is there any built-in api/code for Xcode that allow the app to detect what other social media apps installed in the iphone/ipad/ipod touch to populate out the sharing features?
I was told that Android has such capability, so does iOS have it too?
Twitter integration is built into iOS 5, check this link http://developer.apple.com/library/ios/documentation/Twitter/Reference/TWTweetSheetViewControllerClassRef/Reference/Reference.html
For Facebook you need to use the Facebook SDK, check here http://developers.facebook.com/docs/reference/iossdk/
Alternatively you could try ShareKit... http://getsharekit.com/
Or GetSocialize... http://www.GetSocialize.com/
Both of these offer drop in functionality.