[grey_goose]

I've done something similar, by creating a plugin.

Hook Location: global_bootstrap_init_start
Title: Current Timestamp

$timeplugin = time();

vB_Template::preRegister('forumhome_lastpostby',array('timeplugin' => $timeplugin));
vB_Template::preRegister('threadbit',array('timeplugin' => $timeplugin));
vB_Template::preRegister('USERCP_SHELL',array('timeplugin' => $timeplugin));

You have to register the variable in each template you want to call {vb:raw timeplugin} in. I wanted a UNIX timestamp, but you can either use {vb:date timestamp[, format]} or format it in the plugin with date_format. You can also call it anything you want -- I used "timeplugin" to remind myself of where I was getting the variable from down the road and to avoid any potential conflicts with 'timenow'.

There might be a better way to go about this, but since no one else answered...