Interesting. Based on what I found when searching, I knew there were issues on x86_64 so I assumed this was one of them. I hadn't even thought of the possibility it was TCL (I've probably built 4.0.10 a half-dozen times with different versions of TCL) but I compiled/installed TCL 8.4.11 as well. Seems like this might be a problem with the latest version of TCL.
My original question still applies, though :)