The most recent version of the Amazon Linux VMI (2015.09.1) seems to install version 2 of Puppet by default.
However, if you need to install Puppet 3, that is also easy enough.
Just type in the following to install it:
sudo yum install puppet3
If any errors pop up in respect to incorrect dependencies (this can happen if you installed puppet 2 first), just remove these – they should be reinstalled with the correct version for puppet 3 upon running the above command again.