Description of problem: I think the x86_64 glibc and/or gcc has some sort of generic problem that leads to spurious double free or corruption aborts (either that or several programs have been busted forever). When I boot (see Bug 196419) /sbin/kpartx crashes with this error. Just a little while ago I was using find, xargs, and grep to search all the files in /usr/share and grep got the same kind of crash. Maybe you should revert to the gcc/glibc FC5 uses :-). Version-Release number of selected component (if applicable): Not sure since I don't have the system booted at the moment, but it is FC6t1 with all the latest updates applied as of the date on this bugzilla. How reproducible: The /sbin/kpartx crash happens on every boot, didn't try to reproduce the grep crash.
Another probable glibc problem: If I run Gnu Cash and click on "Help", the "yelp" program comes up, draws the initial screen, then immediately crashes. Haven't confirmed this is another glibc corruption bug, but it wouldn't surprise me.
If glibc report a double free corruption, it is a bug in the program in which it happens. You need to report it against the program in which it happens.