I just wanted to update everyone that our data center did report back that there was some fiber work being done by Level 3 in Atlanta that could have caused some issues. This should be complete and the latency issues resolved - so please let us know if you are still having issues.  It may very well be that Comcast is throttling downloads from sites that you download heavily from as well - but this Level 3 issue in Atlanta is the only thing we could pinpoint from the trace routes that you have provided.

Here are some interesting threads about how Comcast throttles individuals that pull high volumes of data:

http://forums.comcast.com/t5/Basic-Internet-Connectivity-And/Massive-Downstream-throttling-by-Comcast-It-s-getting-ridiculous/td-p/975569

http://forums.comcast.com/t5/Basic-Internet-Connectivity-And/Help-I-need-to-have-throttling-stopped/td-p/1257815

http://forums.comcast.com/t5/Customer-Service/Confirmed-with-tech-on-phone-I-am-being-throttled-because-I-am/td-p/1290843