The Amazon Kindle fire was recently rooted and already has a popular rom running on it. Well somewhat running anyway there are still bugs. Cyanogen Mod 7 was ported to the Kindle Fire by an XDA member, Jackpot Calvin.
Many main things like Wi-Fi and touch input are working but there are some bugs that are causing the release of the rom. Now you soon will be able to run CM7 on your Fire, but it will come at a loss. The main selling point of the tablet is Amazon integration, but with CM you will loose that integration but gain the Android experience.