I know that all meat has guidelines to go by for ensuring the killing of all pathogens, but from a microbiological standpoint, let's look at some things. First, what are the most salient threats? Parasites including bacteria, giardia, tapeworm, and trichinella come to mind. Now the latter three are unlikely to be in most meats, anyways. Bacteria will be in meat no matter what. As soon as you cook it and it cools down, there is going to be some aerobic bacteria colonizing it (statistic - about 1/3 people carry the staph bacteria, staphylococcus aureus, on them at all times. Also, we ALL have E. coli living in our guys - it's just a few rare strains that can harm us).
But the fact is, once meat cools, it's not like it becomes toxic. If parasites were already in it, a lot probably died if they were allowed to reach 108 degrees (that number is significant because proteins in ALL organisms denature and are rendered useless at that temperature). Those that didn't may still be around, but if they heated up, they have mechanisms in place to protect against the heat, which actually mitigate their ability to reproduce.
So worst case scenario, you still have parasites in your meat, which were already there to begin with. If you decide to cook to the specified temperature to whatever the meat is, then you will kill everything in there. So I respectfully disagree with the posters here who said to chunk it. You may have some texture issues given the lack of consistent temperature the meat was cooked under, but regarding safety, the guidelines can be superseded by practicing standard microbial sterilization (heat to kill!)
Any curiosity about this type stuff can be satiated by going to a site like
www.pubmed.com - it's hosted by the NIH, which catalogs all peer reviewed journals (about 30,000 of them), including the bible for this area, the Journal of Food Science. It takes some getting used to (the parsing of information can be a little vexing for a non-science geek), but it's manageable. Further, my degrees are in the sciences (molecular biology, chemistry), so I know a little about this stuff. Any more questions, drop me a message!
-nmr