The revision number should be on the dell product page. Failing that, the revision number Is on the back of the monitor, on the same sticker as the serial number.
As far as I know dell have only released two versions of that monitor, A00 and A01. I believe the change to A01 alleviated some input lag problems.
I am pretty sure that it is not possible to update the firmware revision, if there was a hacky way to do it, it would definately invalidate the (awesome) dell warrenty, so very
much not recommended.
Edit: Ah, a02 released, check your sticker and see if you got lucky.