If you strftime to show the hour and minute too, you will see as I
previously said it is showing you the time in UTC (as determined by how
many hours is it out).

I made a test with date 2009/05/07 using
<dtml-var "fecha.timezone" > -- dmYzZ=<dtml-var fecha fmt="%d/%m/%Y %z %Z"> -- c=<dtml-var fecha fmt="%c"> -- x<dtml-var fecha fmt="%x"> -- X<dtml-var fecha fmt="%X">

and show this

<bound )="" 07="" 05="" 2009="" datetime(="" of="" datetime.timezone="" method=""> -- dmYzZ=06/05/2009   -- c=05/06/09 19:00:00 -- x05/06/09 -- X19:00:00</bound>

here I see what you said me, the hour is gmt-0500.

If add in zope.conf
    <environment>
      TZ America/Mexico_City
    </environment>

or in runzope.bat
@set TZ=America/Mexico_City

nothing change, render the same what before add TZ

now, how I can show the correct date? help please
I use MS Sql Server 2000 with field smalldatetime
I never used before timezone.