Despite having tested it on my Mac box as a regular user, root and nobody (and a couple of other variations) I've been receiving sporadic reports of failures to File::HomeDir, and thus Template Tookit, on "Macs" (with mixed levels of details what people mean by that specifically).
I haven't been able to replicate these problems on my little testing Mac.
Stephen Steneker has managed traced this to a broken version of Mac::Carbon.
File::HomeDir 0.64 contains a small update to Makefile.PL which forces a bump in the required Mac::Carbon version.
I'll also shortly be bumping AppConfig and Template Toolkit to force these dependency updates through (once I'm sure it's working).
As luck would have it, I now have in my lounge room a free loaner 4-CPU Xeon X-Serve courtesy of Sydney advertising startup LocalVision, so I'll have a direct ability to test this properly.
I have to say, the box is suitably scary looking