I personally use a modified hand truck modified with a set of forks welded on
so that they are just longer than the depth of the hive (such that the hive can
easily be picked up from the back).  Also added some eye hooks to the
upright pieces of the hand truck so some budgie straps can be used to
secure the hive to the hand truck.  It seems to work pretty well moving hives
via a low trailer.

The hard part is getting them on and off the handcart.  I'm making some
hive stands with a notches underneath so it's easy to slide the truck
underneath (and the ratchet strap I use to keep the hive together too).
Two person movers are out for me, and getting them on/off the trailer or
truck only solves part of the problem.  With the rain we had this spring
I had to move several hives 400-500' into an orchard, and the hand truck
worked quite well.

-Tim