Hi,
The current released packages include all the available skins. If you login to your site and click the key icon to get to the admin menu then click site settings, you can choose the skin from the droopdown list.
If you want the very latest code you need Visual Studio 2005 or 2008 and you can create your own build.
You can get the very latest stable code from svn trunk, see documentation here:
http://www.mojoportal.com/tortoisesvn.aspx
After you build the solution, you can package your build without the c# source code using the free tool UnLeash It:
http://www.mojoportal.com/deploymentfromwindows.aspx
There is some good stuff in svn trunk that is not yet in the packages release, like the tab layout controls used in Site Settings and Page Settings.
Hope it helps,
Joe