Actually - see here: http://community.invisionpower.com/topic/335962-converge-joomla-160/page__fromsearch__1
I've tried getting Converge to work with Joomla 1.6 and it just won't. I haven't tried in a while, so perhaps something has changed. I gave up and was less than impressed with the lack of support from IPB on what I thought was an official OPB product!
But if it's as simple as that how come sites like wordpress.org, and blogger, or even myspace and so on aren't hacked day in day out? They all allow users to heavily customise their pages or blogs and appear to keep them safe and secure.
I know what you're trying to say Brandon, but I'm afraid I think it comes down not to vulnerabilities but vision. If IPB wanted to create a secure means of highly customisable blogging then they could do so.
Your blog system is rigid and secure, but far too rigid for today's web2.0 communities I'm afraid for it to be a viable contender ... and especially a contender you have to pay for!!!