In reply to spartafan:
You can get a very rough idea of how much snow is left from the Ben Nevis webcam.
Not been up recently myself but for this time of year there's probably isolated patches of snow on the tourist path (presuming this is the route you're looking at), with more continuous snow over the summit plateau and last few few hundred metres of elevation.
I would personally take an axe and crampons if I were doing it at this time of year, but having said that there will inevitably be hundreds of tourists walking up this Easter weekend in shorts and trainers...