I found an interesting study while doing some research. Pine is the most common rodent bedding out there and there's alot of "hype"
http://www.bedocobs.com/uploadedFiles/Technical/EvaluationofMicroEnvir.ofmiceonvariousbedding.pdf
THis article was particularly looking at amonia levels in different types of bedding (note that amonia levels using Carefresh were so high they removed it from the study after two weeks)
In the Discussion section of the study if you can grit through it, it talks alot about consequences of different bedding types. Cedar is defenitely BAD causing elevated liver enzymes, decreased sleep times, etc. UNtreated Pine hasd similar results with liver enzymes and sleep cycles, HOWEVER Autoclaved pine (Had to look up that term, means heated to be sterilized AKA Kiln dried) did not show any such effects on the mice.
Also interesting to note, that although the corncob bedding provided one of the lower amonia levels, it also caused a decrease in breeding success (fewer pups weaned and few pairs bred)
Anyway some interesting reading. Along with a few other sources that I was checking out I am VERY comfortable using kiln dried pine for my rodents in the very least, and I'm going to continue to research as far as using it with the reptiles.
The info that I've found so far seems to indicate that as long as the pine is heated and dried, and isn't too dusty, it would probably be okay, and considering that I pay $25 for a 24qt bag of Aspen, vs $15 for a 4 cubic foot BLOCK of pine... it's rather attractive!