That's what I assumed.  But I had thought that the $Id: $ tag would be
  represented in localtime.  Thinking about this, that doesn't seem to
  make much sense, or maybe I'm just confused.  Probably the latter. ;-)

One could do that (apparently with -z), but I think one shouldn't.
Files don't have timezones, people do.  The Id tag is useful as a
permanent reference that survives the file getting printed, moved
around, etc.  So really it should be in UTC.

perhaps OT, but I'm really glad to see 'date -u' say UTC instead of
GMT (on 1.6.2).  Unknown TZ values still print as GMT, though.
 
-- 
        Greg Troxel <gdt@ir.bbn.com>