the first one was from awhile back on the "blizzard is hiring page" which specifically said looking for people who know how to code ads into video games for an mmo. obviously wow is their golden cow and doesnt need ads.
the other three are all from various interviews most during blizzcons.
simply doing a google will eventually bring you to most of them ive pointed these things out in titan threads many times before. also let me remind you that there is no such thing as a hardcore raider in wow. wow was specifically designed to be the easiest mmo since inception