Kindle Fire’s are just arriving on people’s doorsteps, but the first step to installing custom firmware, rooting the device, has already been done.
XDA forum user death2all110 was poking around for root access and found it pretty quick using SuperOneClick. Right now, this doesn’t mean you’ll be able to install custom firmware, but it shows that custom configurations will likely be possible in the future. Hit up the link below for a full guide on how to root it yourself.
How-To Get ADB running AND Root with SuperOneClick | XDA Developers Forum via The Digital Reader