wetsleet: I don't get it. How can any 'digital' ND filter recover detail which was burnt out in the sensor? Likewise, how can a 'digital' HDR produce a dynamic range greater than what was captured in the sensor. It is not possible to digitally 'magic-up' information not recorded by the sensor.
So these digital techniques are surely more akin to the dodging and burning of the darkroom days, where the dynamic range limitation in question is that of the paper, not of the negative. As such, they are no substitute for physical filters, which will adapt the dynamic range of the scene such that scene can be recorded, albeit with the scene's original dynamic range distorted to fit within the limitations of the sensor.
A lot of DSLRs (and I dare say maybe some up market compacts) have HRD option built into their bodies - I have this on my Pentax Kr. Set up for HRD the camera automatically takes three frames - +3, normal, -3 EV - and then this is processed in about 15 seconds. I understand Nikon has gone a step further and their HRD program shoots five frames bracketed between +5 and -5 EV.