Want to install regular Android on that brand new Kindle Fire? You may be out of luck. A user named kinfauns on the XDA Developers Forum has said that he has taken a look at the software update packages for both the new Kindle Fire and 7-inch Fire HD.
The MLO (xloader, 1st stage bootloader) is signed and the boot header is the type used for HS (high security) OMAP devices with the M-Shield turned on.
This pretty much means both devices appear to have complex protection, including locked bootloaders. Of course this doesn't mean it would make installing Jelly Bean impossible, but it will likely make it much more difficult to do.
...it will be considerably more difficult to manipulate these devices than their 1st generation cousin.
You may want to avoid a new Kindle Fire if you want to get out of Amazon's ecosystem and opt for a Nexus 7 instead.
Amazon's new Kindle Fire HD was announced on September 6, along with new Kindle eReaders. The regular Fire had a spec bump, while Amazon also introduced two brand new models, the Kindle Fire HD 7-inch and the Kindle Fire HD 8.7-inch, the latter includes dual band 2.4GHz and 5GHz band support, MIMO support, an OMAP 4470 processor, and storage options starting at 16 GB.