As luck would have it that's in the new implementation, I had already considered the same thing

. Right now the current ROM doesn't support anything other than weathersnoop devices and "indigo thermostat" devices, but the new version supports using any state from any device to get the values that you want to show on your pages.
Right now I"m about 80% finished with the new ROM, if I keep on this pace then by this time next week there should be a new version (fingers crossed).
That being said, however, I'll be releasing the part you are most interested in probably in the next few days, just not the entire soup-to-nuts ROM 2 for a week or so.
P.S. - I messed up when I uploaded 1.1.2, I just re-uploaded it with the change.