Doing the same thing for the webapp is also useful--it serves as visual reminder to QA folk that the production box (white background) is /not/ someplace they should be running test scenarios (vs. the QA box with an orange/whatever background).

Also, you can use different colors for different QA boxes--"I need blue qa deployed" or "That fix is in black qa".

(Yes, this was an enterprise environment, why do you ask?)