Open Source alternative to System Center

I was looking for a good way to manage software deployments at one of my customers. They currently use System Center (2007) to package and deploy software to workstations and manually install software to the Citrix farm. We most likely will just go the Microsoft route, but there are some limitations in the types of deployments you can use (MSI only). In doing a bit of research I ran across WPKG, and open source automated software deployment, upgrade and removal program for Windows. This is the article I found on the Citrix forums:

Obviously there are a number of different ways to deploy software, I am looking for one that will work until we move the PVS, then I will just update the vdisk image and reboot the machines.