Hi! What will happen to my unlocked and jail broke iPhone if i have downloaded the latest version of iTunes and use the downloaded applications in it in my iPhone? Will it cause my iPhone to restore to its original setting and do i have to unlocked it again? Please help me.. I'm scared to try this because it is so expensive to get an iPhone unlocked. Thanks in advance.
If you install the latest version of iTunes, the next time you plug your iPhone in, iTunes will force you to update your iPhone to the latest firmware version or you won't be able to sync your iPhone anymore.
But, you can unlock your iphone again yourself. For this, I keep referring my friends to http://www.iphoneunlock2.com I've personally used it to jailbreak my own iPhone 3G and to unlock my friend's 1st Gen iPhone. Really easy to use, and definitely NOT "so expensive" 
Good luck!
If you install the latest version of iTunes, the next time you plug your iPhone in, iTunes will force you to update your iPhone to the latest firmware version or you won’t be able to sync your iPhone anymore.
But, you can unlock your iPhone again yourself. For this, I keep referring my friends to http://www.iphoneunlock2.com I’ve personally used it to jailbreak my own iPhone 3G and to unlock my friend’s 1st Gen iPhone. Really easy to use, and definitely NOT "so expensive"
Good luck!
References :
http://www.iphoneunlock2.com