Many software solutions are 'going hosted' these days, and Drupal is no exception.  A startup called Acquia uses the open source project to provide a free Drupal distribution along with commercial services, support, and hosing.  The same developer who created Drupal, Dries Buytaert, is now Acquia's CTO.  In roughly three months their hosted version of Drupal, called Drupal Gardens, will finish its current public beta phase.  

There are currently a few thousand users right now for the public beta.  Drupal is a platform for publishing websites and managing its text, image, video, audio, and other content.  You could make a strong case that Drupal is the most popular Content Management System right now with some high-profile use cases.  The White House, NASA, and the Mayor of London's website all use Drupal.

The Drupal CMS may not be as easy to use as some competitors like Wordpress and Joomla, but the greater amount of freedom and customization along with the sheer volume of add-on modules makes it more powerful than the other platforms.  Drupal Gardens is based on Drupal 7 and it comes bundled with some "must-have" modules.  It will also come with Acquia's more user-friendly interface.  

Acquia's goal is to take back some of the low- to mid-end market from simpler platforms like Joomla and Wordpress.  Drupal is targeting businesses who want to set up "micro sites" to manage projects, events, and ad campaigns.  The route to Software-as-a-Service for Acquia was the reverse of well-known SaaS  vendors like Salesforce.  While Salesforce started with SaaS cloud services and then provided a Platform-as-a-Service, Acquia began with the platform (open source Drupal) and then moved to a hosted SaaS.  This means Drupal Gardens is coming into the web ecosystem with plenty of custom functionality already. 

                                                    

Another great thing about Drupal Gardens is that even after the GA release, the service will be free (as in beer) throughout 2010.  After that, Acquia will start offering a basic service for free along with two subscription plans with more advanced features.  The two plans will cost $19.95 and $39.95 per month.  The great thing is, if a customer wants to switch from the hosted service to an in-house implementation, they can just download the Drupal Gardens source code and cancel the service.