I was very nervous since this is a bit more involved than the other phones I've worked with. However it went flawlessly without even a single glitch!
Of course you have to follow instructions and there are a couple files you have to download but it's all there in the instructions.
I don't know what methods everyone is using but this is the way I went.
[SCRIPT] Windows One Click Root Method [3/26/11] - xda-developers
And for those that do not have the Android SDK and the path and all that set up, here is a link to a program that will install everything you need and also set your path for you. It also installs the drivers for the phone. This is real nice for those that are uncomfortable with the ADB stuff.
[Prerequisite to Rooting] Android SDK Installer - v3.0 for Windows - xda-developers
Here is also a link to all the files you will need for the process
Index of /thunderbolt
I paid full price for my phone so I was a bit shaky during the process... LOL... thankfully it was very painless. Before you jump in, read up on the process.