Facebook recently has been rolling out the ability to email to and from the "messages" interface. This is rolling out with the update that combines Facebook Chat and Messages, etc, into one messaging service (still usable separately, but all of the history is saved in Messages).
This may still be a limited BETA, but I have it, and I know many who do.
I do not know of anyone who uses it though. The attachment manager, layout, and usability are very streamlined and modern. I feel that it brings the concept of email up to 21st century, personally, though it may be unprofessional, it is still great technology.
Or am I missing something? Is Facebook email unusable or just unpopular and why?