Will contain more Puppet on Ubuntu details.
Backport version on Lucid 10.04
Just in case anyone else is trying to use the 2.7.1 version of puppet from the lucid-backports repository on lucid (for example, to use with clients running a later version of ubuntu and thus running a new version of the agent), this doesn't work due to a problem with ruby not being able to verify the certificates on the agents.
It also will not work to run an older version of puppet as the master and a newer version on the agents, at least not fully. It will appear to work, but none of the configuration catalogs will actually make it to the agents.