You can't use PHP in templates, except for declared variables. Though, you could use the phpinclude template, but if you want the current date, it would be a lot easier to just set $today = date(); in the php file, then in the template use $today.
If you want all templates to act like the phpinclude template, I would look at how the phpinclude template is managed in the PHP files...
Though, I would just use the following hack:
http://www.vbulletin.org/hacks/index...ck&hackid=1200