Hi Oz,
that's an easy one, I got it from Katrins latest book:
At first I converted it to b&w with a channel-mixer layer, monochrome checked and used the red channel 100% and some of the others. Then a selective color layer, tweaked the colors a bit to bring some detail into the picture
Katrins trick:
A color-balance layer. The shadows have more blue and less red, the highlights vice versa. The settings were something like:
Shadows -20/0/+20
Highlights +20/0/-20
Tell me if I didn't explain that properly please