The Official Gmail Blog shows the evolution of Gmail Chat. In it, they describe having a usability lab to test out new features and ideas. The feedback from the testers are used to help guide their decisions. TechCrunch gave a peak inside Gmail’s Usability Lab. As can be seen, it is not some big lab with a two way mirror. Their lab is just a small room with a computer and some video equipment which any company on a budget can setup. I think what is most interested is that despite all the different iterations of Gmail chat seen from the links, Google eventually ended up with a very simplistic lightweight application. Sometimes, less is more.