I think what youre asking is the transfer of files between apps- that is through a vey handy in-phone app called ifile and on your desktop you have limited flexibility w itunes and complete access w iFunbox.
This. Once you have iFile on your jailbroken iPhone you can move files around, and actually 'save' folder extensions to find later. However, navigating around the root files of an iphone is an exercise in frustration, trying to find the one file you want. That is, until you just aboutmemorize where everything is.
IFunbox on a Mac or PC makes life a lot easier.
And there was a previous post in here talking about how Android phones can be made to have the UI look like WP or even iOS. Well, same thing can be done with an iPhone via Dreamboard tweaks in Cydia. The iPhone UI can look like Windows Phone, OSX, Windows 7, Android variations like sense from HTC and so on.
All that said, I got fed up with the cat and mouse game with Apple. You have devs crack the OS via an exploit, so everyone can jailbreak. Then Apple will put out a patch to fix the exploit and if you mess up your jailbreak with a tweak that has major conflictions with other tweaks you have installed or you accidentally hit the ota update, well you were screwed. Jailbreak gone. Strides have been made so you can now always downgrade, regardless if Apple is not signing old OS updates, but it requiresmore work by the user.
(by the way, anyone that said that jailbreaking was a difficult process and rooting was easier, hasn't jailbroken an iphone. Both are so easy a caveman can do it.)
Sorry for the lengthy post. I bought an S2 a while back then got one of the first AT&T S3's. Unless Apple creates a phone that prints money, I'll likely never buy another iphone. I just wanted to chnge some bad info posted earlier in this thread to good info.