*** NOTE *** This is now resolved. The problem has nothing to do with OSX, but is due to the fact that the version of tar I'm using defaulted to --format=posix rather than the traditional --format=gnu (it appears that this is a recent change in my linux distro -- OpenSuSE). It was also reported to me that other recent modules in CPAN are exhibiting the same behavior, so this problem may become more prevalent in the future. See comments below for more details.
I've had three reports of people unable to install Date::Manip from CPAN on OSX. Unfortunately, I do not have a mac so I haven't been able to do any testing/verification (so I'm definitely sorry about not being able to provide more information).
The problem comes from using the Makefile.PL to install it (if you remove the Makefile.PL and use the Build.PL install script, it works fine). My guess (totally unverified) is that it is somehow related to the number of files. There are hundreds of timezone related .pm files to install, and the number has gradually increased over time, and I suspect that sometime in the past year, the number increased such that there is a line in a file generated from Makefile.PL during the install process that is now longer than some threshold and is causing problems.
The error messages reported look like:
There is no PaxHeaders directory in my package... it is something generated during the install process (and I'm not familiar with the OSX install process at all).
The Makefile.PL that comes with Date::Manip is absolutely generic... nothing special at all, but is there something that I can add to it to avoid this problem?
Sorry for not being more help... normally I like to be more educated about my posts, or have done more of the background work, but in this case, I'm not able to do much.