I've just set up syntax highlighting for Puppet manifest files, and thought I'd share the simple steps. The first thing to do is download the syntax file from http://www.reductivelabs.com/downloads/puppet/puppet.vim and save this to ~/.vim/syntax/puppet.vim. Now when the filetype is set to "puppet", vim will use this syntax file.

That's useful, it it would be even nicer if we could make vim know that files ending in .pp were puppet files. Turns out this is very easy to do. You need to create a file to detect the correct filetype when you open a file. You need to put the following lines in ~/.vim/ftdetect/puppet.vim:

au BufRead,BufNewFile *.pp   setfiletype puppet

Now when you load a file ending in .pp, you should get nice syntax highlighting. You can also make vim use special settings for the puppet filetype by creating a vim script file in one of ~/.vim/ftplugin/puppet.vim, ~/.vim/ftplugin/puppet_*.vim and/or ~/.vim/ftplugin/puppet/*.vim. Vim has a lot of flexible hooks to enable file type specific configuration; hopefully it should be fairly easy to modify these examples for other file formats.