Google Apps Mail won’t let me view PDFs in browser anymore

Easy to fix when you know how to fix it. In Dec 2008, Google introduced a feature:
Gmail now lets you view PDF attachments right in the browser if you prefer not to download the file to your computer.

The missing bit of information? You need to make sure you’ve got Google Docs added as a service in your Google Apps Domain settings. See Dashboard / Add more services / Select Google Docs.

As Gordon Ramsey would say “PDF viewer in browser… Done.”