In the article Ethnicity, Ethics, and the Deaf-World by Harlan Lane, the author makes a strong case for the Deaf-World to be considered an ethnic rather than a disability group.  Lane provides a framework, and some historic, cultural and anecdotal supports for the argument. Harlan Lane is a prominent spokesperson for the idea of recognizing deaf ethnicity, and writes and lectures on the subject: http://www.rochester.edu/news/show.php?id=7102 

Overall, I agree with Lane.  In my own experience, deaf people very much have a culture that few hearing people ever connect with, much less are a part of.  I worked for a time as the dinner cook at a historic residential school for the Deaf, which was a great experience for me, and really a privilege to be even a small part of the community.  It only takes a brief time to realize that there is as much diversity within any demographic group as there is between demographic groups.

Years before I ever worked at a school for the Deaf, I was working in an Italian restaurant when a large party of Deaf people came in to eat.  The regular waitress couldn't serve them, and though I didn't sign at all at the time, I took their order and had a great time serving them.  I was shocked at the tip they left me, which included a note about how much they appreciated having a relaxing meal.  It made sad, at the time, to realize that they usually must have awkward or bad experiences when out in the hearing world.

"Difference and diversity...are a major part of what gives life its richness and meaning..." Lane (2005)

Reference:

Lane, H. (2005). Ethnicity, Ethics, and the Deaf-World. Journal of Deaf Studies and Deaf Education, 10(3).