There is a custom build of Android 3.0 (Honeycomb) available for the Nook Color. This particular build is designed to run from a MicroSD card (opposed to some of the Froyo eMMC versions which reflash the internal memory), albiet I am not 100% if it requires the Nook Color to be rooted...
On a MacOS system, download the image and do the following:
The disk image will take several minutes- depending on the write speed of your MicroSD.
Once complete, shutdown your nook, insert the card and you should see the Android boot lolo on power-up.