Wasn't there a slashdot reference to an article in the last week where Microsoft "was considering" removing admin access from their employees? That doesn't sound like "eating their own dogfood". As long as they're all running Windows with the highest access levels (admin), they're potentially missing serious security problems.

I thought the idea was to see if the system was usable without admin privileges. Haven't some people argued that it's too much pain to run as a non-privileged user? that people are almost forced to run in admin mode which generally makes the system more vulnerable?

So may be dog food is "non-admin mode is usable". And it will help identify the tasks the actually require privilege escalation. And help reduce those tasks or ease the process in some way.