The term real time is pretty broad, and I think most of us would be happy with seconds per frame vs. minutes or hours.  Something that I was just thinking is that the main difference between real time and even GPU renderers is that real time engines only show their output differently.  No matter how fast computers get, Poser's Firefly can never be real time because it calculates buckets to the screen rather than a framebuffer.  Unless the buckets were filled and moved to the buffer in less that your frame rate, it's a process you'll always be likely to see.