Exists a way/SDK for developing plug-ins for mobile version of Safari browser on iPhone and/or iPad in Objective-C exists?
I have seen some possibilities for jailbroken devices ( http://www.macstories.net/news/yes-you-can-create-plugins-for-iphone-os/ ) but this is not an option for me...
You cannot write plug-ins for Mobile Safari unless you are developing for jailbroken devices. There is no (public) API for it.