Fabric is more of a task-oriented SSH replacement with some really nice bells and whistles, much different from Puppet or Chef. Some folks are working on Salt Stack which is python-based and more akin to the others.
Fabric is more like Cap than Puppet / Chef
bcfg2 I have been using it for a few years now. Have enjoyed it much more than the other similar tools we evaluated: puppet, chef and cfengine
bcfg2 I have been using it for a few years now. Have enjoyed it much more than the other similar tools we evaluated: puppet/chef/cfengine