I am new. And I need help.

[savvytech]

Hi there. My friend's iPod Touch 3g is at version 3.1.3 and she wants to upgrade but when she opens up iTunes, it tells her that she can update to 4.2. I tried searching for a jailbreak, but I cant find one for it. So can anyone help? She wants to at least have it at 4.x so that it will be ready for iOS 5 when it comes out. Please help.