XDA member and veteran Android hacker verygreen posted instructions and a proof of concept video this morning.
His method requires a small amount of typing and does not look all that difficult for the average user. This particular trick is probably not going to be of much use. It's dependent on a mistake made by the software developers working on the Nook HD.
I don't see that there has been much mention of this in the blogs, but the Nook HD+ (and probably the HD as well) was released to consumers with several developer setting still visible. Of particular use is the ability to enable ADB. This setting is the first step towards rooting and hacking an Android device because it lets you plug the device into a USB cable and access the device from the computer at the other end of the cable.
I expect B&N to remove this option with the next update (2.0.3), but until they do so hackers will be gratefully taking advantage of this handy shortcut. I expect it to speed up the development of a hack which installs Google Play and other Google apps.
Update: I have just learned that this hack is not repeatable. According to an update over on XDA Forums, several users have reported going into a reboot loop and having the HD+ do a factory reset after the 8th loop.
via XDA Forums