gistfile1.builder

class IO
  alias :old_puts puts

  def puts(thing)
    if not thing.to_s.match(/\A\*\* Erubis [\d|\.]+\Z/)
      return old_puts(thing)
    end
  end
end

$stdout.puts "foo"
$stdout.puts "** Erubis 2.3.4"
$stdout.puts "bar"

=======================

pleb:~ will$ ruby puts.rb 
foo
bar

Or just pipe yer output through grep and do away with patching a core class.

Julius:~ caius$ ruby -e 'puts "foo"' -e 'puts "** Erubis 2.3.4"' -e 'puts "bar"' | \
> egrep -v "^\*\* Erubis [0-9.]+$"
foo
bar