Just a little more info guys....
The SMF default theme (ironically) is not the theme used on this forum however you can change to any theme including the SMF default theme from your profile. The theme we use on here is the Classic theme.
We are working on getting it so it displays which members are in the chat room from the main forum and obviously a proper chat button. Unfortunately this means editing some of the forum code and we're also looking at having a new theme for the forum. It makes sense to have the new theme in place before fidgiting about with code
Also, guests cannot access the chatroom, which is even more reason to sign up!