horse-sin fixed
EDIT: 18/06/13: Also split upper and lower sections into separate halves for easier re printing if one goes wrong
After 5 failed prints I figured out the original version by Terryr has the two parts at different layer heights - the lower part of the body is approx 0.5mm above the upper part, so gets printed floating in the air (and thus doesn't stick to the bed). If you look carefully in the thingiverse view, you can see the shadow under the plate (which using 0.4mm layer height doesn't print out).
It's quite easy to fix in Blender, but I've uploaded a fixed stl. There are a few holes in the Blender exported mesh (there were in the original too), but it doesn't affect slicing with Skeinforge.
To print it I added a single layer-height plate from the tail to the rump of the upper layer, as my glass/ABS juice adhesion isn't good enough to hold the tail with such an overhang and a small adhesion surface. Also I needed to slow printing down for the legs as they came out spindly and a bit distorted. To do this (with Skeinforge) I activated cool, set cool type to slow down and set a minimum layer time of 15secs. Also you definitely need the extruder fan on or the legs will wobble and not adhere properly.
To cope with the dramatic overhang of the tail in the back/top section, I created a minature raft (see printer-host image):
I use repetier-host, so just created a cube in openScad of height 0.4mm which I dropped into the scene and aligned with the rump and tail for the back section (the leg section didn't need anything as the piece was too small/too little overhang to need such a raft. If you wanted to you could easily do the same in Blender before exporting.
Once printed with ABS, it glued together beautifully with acetone.