This was a nice shot - both photography and espresso. I was using the SB-600 in i-TTL mode (wireless slave) laying on it's back shooting from the right side. The D200 was up pretty close and set to f/2.8 (I think). Same setup was used to capture this water flush on the Brewtus II.

Check out the detail at the mid-point of this water column. This is a tight crop of the image above, showing the microscopic bubbles trapped side-by-side with the larger bubbles. Amazing.