This is particularly challenging if you are seeking to leverage a substantial collection of heterogenous Open Source tools.
Capistrano was mentioned by Martin Fowler in his paper on Continous Integration.
http://capify.org/
Capistrano is a tool for automating tasks on one or more remote servers. It executes commands in parallel on all targeted machines, and provides a mechanism for rolling back changes across multiple machines. It is ideal for anyone doing any kind of system administration, either professionally or incidentally.
Websphere: Automated Deployment of Enterprise Application Updates, Part 1 - Basic concepts
TFS Deployer interfaces the Team Foundation Server build store with PowerShell allowing script execution to be triggered across multiple machines when a user transitions the quality indicator of a build from one state to another.
Robocopy
A command-line directory replication command. It was available as part of the Windows Resource Kit, and introduced as a standard feature of Windows Vista and Windows Server 2008.
The Windows Installer XML (WiX) is a toolset that builds Windows installation packages from XML source code. The toolset supports a command line environment that developers may integrate into their build processes to build MSI and MSM setup packages.
Ayende Rahien: Requirements 101: Have an automated deployment
IBM Developerworks: Automatic deployment toolkit for an SOA project environment, Part 4: The automatic Build-Deploy-BVT toolkit for SOA projects
