Per default the execution code in a cms-php widget is returning the date.
After you create the widget you have to click on "Configure" on the right and insert my code.
edit: let me clarify that one.
You have to delete that code, which is in there by default:
Code:
$output = date(vB::$vbulletin->options['dateformat']) . "<br />\n";
If you post additional code below that line nothing will happen. It just takes the output value - and doesn't even evaluate the rest.