Not trying to stoke the fire, I'm genuinely curious, but are there any machines that are currently available that are using .55 W/Ghash?
The ASICminer BE200 40nm chip is 0.35J/GHash at rated voltage. Though as usual people will over clock them straight away thinking more is better.
Here is a neat little video of BE200 immersion testing.
http://vimeo.com/98321051