i got the twitter app free from the app store and i couldnt login it kept staying on authorising..
i found the problem so if your ipod/iphone is jailbroken and you have vwallpaper installed uninstall it in cydia and uninstall skrewcommon and twitter should work if you have zRingtonesHook.dylib installed that causes problems for twitter aswell so uninstall that if you want twitter to work hope this helps