Puppet Labs is the developer of Puppet, software that applies declarativeprogramming to the task of system administration of compute, network, and storage infrastructure in traditional data centers or in the cloud.
The Cascalog system has combined the Cascading system for abstraction of advanced data processing on Hadoop and other systems, the Datalog declarativeprogramming language that is well suited for expressing database queries in an abstract form, and the Clojure language to create a declarative language for queries that can be run on Apache Hadoop.
The state of the art in this model of programming is Pegasystems, which is often called a BPM system but is really a declarative application development environment.