Not really. Phorum templates and Smarty templates are a different beast and won't integrate without doing some integration work.
You would first have to create a header.tpl for Phorum in which you load the smarty system and parse the smarty template.
After that, you would have to extend the smarty header to include all required bits for Phorum. In the header.tpl of Phorum you will see a lot of dynamically added code that is required. The template data can all be found in $PHORUM['DATA'] and you'd have to let your smarty template include these bits when included from the Phorum environment.
Maurice Makaay
Phorum Development Team
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