要用jailbreakme.com 3.0越狱iDevice, 固件版本最好已经升级为4.3.3
下面是 iOS 4.3.3 Apple网站的下载链接:

Download iOS 4.3.3 / 4.2.8 Direct Download (Official from Apple)

    * iPhone 4 (GSM)
    * iPhone 4, iOS 4.2.8 (Verizon)
    * iPhone 3GS
    * iPad 2 WiFi
    * iPad 2 GSM
    * iPad 2 CDMA
    * iPad
    * iPod touch 3G
    * iPod touch 4G


How to restore or update your iPod/iPhone/iPad:

After downloading the desired firmware, you can shift-click (PC) or option-click (Mac) the Restore or Update buttons in iTunes. A file dialog will open and let you choose the downloaded ipsw-file.

怎么恢复或者升级你的iPod/iPhone/iPad？

下载固件后，在iTunes里按 shift-click (PC) 或者 option-click (Mac)点 恢复或升级按钮，出现的对话框选择你下载的ipsw文件。

iPad 2 iOS 4.3.3 越狱教程
>How To Jailbreak iPad 2 On iOS 4.3.3 & iPhone / iPad Touch Using JailbreakMe 3.0