They have been doing increasingly long test flights in different conditions. I saw one flight that went from Seattle to over the Arctic Ocean and back, and another that circled for hours over the Pacific Ocean off of Oregon.
I flew out of KFLL Sunday night and saw it there, unfortunately no camera. The NASA DC-8 can also be seen at KFLL these days. I will be back in FL Friday night and if I am not too late may get to take a few photos