BTW, in addition to the office-supply Elmer's rubber-cement, I've also used SuperGlue, DAP contact-cement, Vittoria tubular glue and 3M Fastak 08031 Super Weatherstripping Adhesive to glue patches onto tubes. They all work fairly well at below insane levels of riding and have lasted me for quite a while. However, on the crazy downhills I do with bumpy tarmac having many 60-> 20mph maximum-braking turns, those have all failed with only the vulcanized patches holding up 100%.

Some good background info:
http://en.wikipedia.org/wiki/Vulcanization
http://www.freepatentsonline.com/4913950.html