ihateyou.pp

if ! $::package_installed {
  file { 'download_rpm':
    ensure => file,
    path   => '/tmp/my_package.rpm',
    source => 'puppet:///files/my_package.rpm',
  }
  exec { 'install_package':
    command => '/bin/rpm -i /tmp/my_package.rpm',
    require => File['download_rpm'],
  }
}

ilikeyou.pp

# Why can't everyone do it the easy way?
package { 'my_package':
  ensure => present,
}