In reply to rubisco:
Yes - you can get to both the Franz Josef and the Fox Glaciers very easily, and there is nobody to physically stop you. You can get right onto them using the paths cut by the guided groups. We did this in 2008 taking our own kit and playing around doing some short ice climbs this way.
However, the glaciers are 'living' things and are always on the move and changing.
In 2008 2 lads were killed at one of the glacier terminal faces when a big bit fell off and landed on them.