Landscape is an easy-to-use systems management and monitoring service that enables you to manage multiple Ubuntu machines as easily as one through a simple Web-based interface.
However, Landscape is not free. The RedHat counterpart Satellite has a free version called Spacewalk, but it doesn't work on Ubuntu. (There is an attempt to port Spacewalk to Debian, but it doesn't look like it's stable yet.)
Are there any open source alternative to Landscape? Better yet, are there any Spacewalk-like software that works for both RedHat-based and Debian-based systems?