Cycleops publishes this..

http://www.saris.com/comparison/trainers.pdf

I eMailed them to see if they could share how they developed this and any raw data and they (Jerrod) said this...

Unfortunately, we don't have any raw data for those. The numbers can change fairly dramatically depending on the bike and the rider, so we just used an average of the results we had here with different riders and powertap setups. What you may want to do if you can't extrapolate good numbers from the online graph, is to find a friend with a PowerTap hub and jot down power output #'s at different speeds.

I did a regression calc in Excel based reading data from the chart for my wind trainer and got this... doesn't mean all that much perhaps, but it's what I've got.

y = 0.8369X^2 - 3.0409X (y is power in watts, x is wheel speed in mph).

I may try an borrow a power meeting to calibrate, but once all this friggin snow melts I think I'll just go out and see how I'm doing on an actual road!!!