The Joomla marketing team has announced that they will provide a Joomla online demo. Like WordPress does with his wordpress.com webservice, but with a special partnership with Siteground hosting sevice.
As joomla is supported by OSM (Open Source matters), a non profit organization, this demo will be open for free. Sitegroung is famous in CMS hosting (Joomla, WordPress and Magento) because they offer specific tools and an amazing dedicated support team.
This is a good step in the direction of the new Joomla users. Indeed, testing an admin interface in one click is always a great promotion tool for a CMS.
Installing a CMS could be a serious impediment, there is no one to question it :)