We just posted to our forum detailed steps how to install the IntelliGantt Web Part for SharePoint on both 2010 and 2007. Yes, we have the full matrix: Foundation, Standard and Enterprise 2010 are supported, as are WSS 3.0, MOSS Standard and MOSS Enterprise.
The idea here is a user will be able to drop the IntelliGantt control into a SharePoint server and evaluate how well it works for them without having to bug IT. But yes, we will have an actual package to install on SharePoint servers properly as well.
In the meantime, though, this is the method. It's straightforward on SharePoint 2010, but SharePoint 2007 makes you go through a particular hoop (which we've labelled as 'Step 13').
Finally, we encourage you to join our moderated forum, where we look forward to answering your questions and providing more in-depth information.