So if you have been holding out on purchasing the Kindle Fire HD 7" because you were waiting for root then wait no more! The root method by developer "sparkym3" is pretty straight forward. It uses an exploit using the qemu local.prop root method! Simply download the root files, extract them to a new folder and run the RootQemu.bat from the directory. It should be noted that the bootloader is still locked down tight, and there is no custom recovery as of yet which means there is no way to make a nandroid backup. I would NOT suggest modifying any system apps. Some people have risked it and lost wifi which has caused some serious problems for them. One person discovered they had lost wifi after adding the Google Services and Play Store. They proceeded to do a factory reset and found that they were not able to set up the KFire after rebooting because the wifi was still not working. Just know that you have been warned.
Root method via XDA