Just a heads up for anyone interested in this change: The patch has been integrated into a branch for a while now and is ready to be tested.
The goal of this patch has been to get the ispCP GUI to work with Smarty templates as easily as possible. Since this goal has been reached I'm now open to suggestions on how to improve the Smarty implementation.
I'm currently testing the branch for functionality whenever I find some spare time but as mentioned before I would be glad for others to test it as well.
You can check out the branch here:
http://www.isp-control.net:800/ispcp_svn/branches/zpin