JTK 2.1 with J1.5 Workaorund code for now.

[admin]

Most Joomla 1.0.X templates will work with Joomla 1.5 but you need to
Put the system into legacy mode. This is done via the Joomla administrator via the CMS’s back-end

Extensions
Plugin Manager
> System - Legacy
> Set to Enabled: Yes

Image code not working because the Globals that where part of the
1.0.X are around with stable version of Joomla 1.5. add this code to top of your 1.0.X templates so the image code works.

PHP Code:

<?php    
$GLOBALS[mosConfig_live_site] =$this->baseurl;
   $GLOBALS[cur_template] =$this->template;
   ?>

I'm working double time on JTK 3.0 Super features coming

Cheers,
Brian