OTA (over-the-air) updates on Android devices often unroot rooted phones, and very often they make old root methods unusable, making users wait for a new root method to come out. Voodoo OTA RootKeeper is an Android app that was made specifically with the aim to preserve root access on a device, which can then be restored after the device has been updated. It also lets you temporarily un-root the device in case you wish do something that would require a non-rooted phone.
According to XDA member indiscriminant, OTA RootKeeper can also be used on the HTC Evo 4G LTE in case you wish to preserve root access while updating to a newer OTA update or firmware. Also, sometimes on Android 4.0, the phone can automatically download and force you to install a new update, so OTA RootKeeper comes in handy there as well.
Using Voodoo OTA RootKeeper is quite simple. Simply install it from the Play Store (Android Market) on your phone, run it, grant it root access, then press the Protect root button to make a backup of root on your device. Now, even if you lose root access after an OTA update, you can simply install OTA RootKeeper again and restore root. OTA updates? Bring them on!