My first image isn't that great for the experiment but I have an idea for another one I can try later (which I'll add in).
First of all I created another creation in Photomatix which looks good by itself...
Then, using PhotoShop I added lens blur to create an out of focus area and drawing the eye to a certain in focus area of the image. This fools the eye into thinking the objects aren't real. Photos should be taken at an angle (the higher the better) to create a better effect.
Its a bit hard to see as a small picture but I'll do a clearer one later and put it up. For more info...
http://www.tiltshiftphotography.net/photoshop-tutorial.php
Another photo I had a go with, still not at a great angle though:
