Do you wave? "Wave, to whom? That person I don't know?" "But why doesn't that person wave back? How rude!" "Hey, I don't know you I don't owe you anything, just let me do my intervals... and please don't draft... let me turn my iPod back on."
What is it with the wave to other cyclists. Do you do it, do you reply if waved to, do you wish we'd stop this foolish act, etc. Waving to other cyclists is mostly done as if we are all apart of some secret non-biological family, some underground club or secret society. The wave can say to the other cyclists, "have a good ride" or "glad to see you bold enough to be out in this weather like me", or a handful of others. One local pro says he makes a point to wave to everybody he see's out on the road but I bet on some days his wrist could get pretty tired out on the roads.
But not everyone waves. I remember when I started out in cycling in the midwest we waved because there were so few of us but come out on a beautiful weekend in Boulder County in March or April and you'd probably come home with wrists more sore than you legs. Do I wave, no not to every single person but I'd say I do most of the time. As cycling grows in the Front Range I might not wave to everyone but I'll continue to wave often.