As an owner of a new nook e-book reader, I've been watching the related boards somewhat.

Occasionally the issue comes up of "if I buy a book from Amazon can I read it on my nook?"

Unfortunately with rare exception the answer is not really.

There are technical ways to make it happen. You'd think it would be fine to download a book from Amazon, run a conversion and upload it to your nook reader. Technically you can. It's also a violation of the letter of the DMCA though more than likely it will be unenforceable in that context if it ever made it to court.

The simple act of having the decryption program on your computer to allow this is a violation of the DMCA. Helping someone find a copy of it is considered "distributing circumvention tools." First time offenders may be subject to a $500,000 fine, imprisoned for five years, or both. That's the criminal penalties. Civil penalties may also be incurred. All because someone wanted to read a book that they bought.