Add JavaScript into a specific content type
I can't comment on the proper Drupal 7 equivalent, but in Drupal 6 sites I do this in a template_preprocess_page.

I will have some logic to make the decision (either based on arg() or page_manager_get_current_page() from panels), and then prepend $vars["scripts"] with the external script.  I prepend so that I don't run into dependency trouble with any local scripts.

I will also sometimes set up a new region called $global_scripts for thinks like Google API and SWFObject that I want to load from a CDN, and this gets printed out before $scripts in the page template.

To be honest, though I normally have all JS on all pages so that the files get cached.