Puppet Labs is the developer of Puppet, software that applies declarative programming to the task of system administration of compute, network, and storage infrastructure in traditional data centers or in the cloud.
By sticking with the declarative model, Drupal Gardens can upgrade layers of software in the background with minimal disruption to the users, who do not have to worry about upgrades.
Dries Buytaert, the Belgian wunderkind who created Drupal, started Drupal Gardens because he saw that Software as a Service could be combined with a declarative configuration model to make the process of creating web sites so much easier.