Good ol' Sheldon Brown's gear calculator page has always been a favorite of mine - it'll give you gear inches, meters development, or speed at RPM for a wide range of conditions...
http://sheldonbrown.com/gears/ If I use a 1" tire for a 559, a 650, and a 700 wheel, it gives the following speeds at either 100 or 120 RPM
100 RPM 120 RPM
559 wheel
33.7 40.5 650 wheel
34.4 41.3 700 wheel
37.1 44.5 Of course, I would imagine that even Sheldon's calculator has to use "theoretical diameter" numbers for wheel/tire figures, not taking into effect the fact that you compress a tire a few tenths of an inch when you apply rider weight.
The southbound part of the HOT Hwy130 ride allowed me to crank up to max speed (i.e., 'spinout'), given the slight downhill grade and the tailwind... My Xstream26 has 559 wheels with 1.1" Duranos, and a 52:11 high gear combo. I topped out at 38mph... 650 wheels would have added another ~1 mph to that, and 700s would have been zoom-zoom!!!