Detect whether Office is 32bit or 64bit via the registry

Question

Now that Office also comes in a 64bit install, where in the registry do you find out if the version of Office installed is 32bit or 64bit?

Answer 1

I've tested Otaku's answer and it appears that the Outlook bitness value is set even when Outlook is not installed, even though the article referenced does not clearly indicate that this would be the case.