Looks like phyllostachys atrovaginata to me. Based on bamboo gardens, it should have the potential of getting up to 2.75X35-40ft, but your soil conditions, and shade might be limiting its size just a little bit.

I posted a picture of my shoots.

Here is a link that might be useful: {{gwi:408613}}

Steve,

I have had various people id it as P. nuda,aureosulcata,bissetii and atrovaginata. Bamboo is not my specialty and really don't know what to make out of all the differnt wide ranging thoughts on what it is. Here is a link to more photos. I would really like to hear anymore feedback you may have. Thanks!
http://s9.photobucket.com/albums/a89/JohnJD/Bamboo/

On a second thought, out of all of my 30+ bamboos, it looks most like atrovaginata than anything else, except the internodes look too long, shoots have too much green, and the diameter of the culms is a bit on the small side for a mature grove of atrovaginata.

It looks like it might be one of the less common species.