Back in November, Google announced themes for Gmail so that you could customize the look of your webmail. While this was a great addition, I hated that I didn’t have it in our Google Apps. Well a couple days ago, I finally noticed the new "Themes" option in my email setttings! It’s pretty neat…I was getting tired of the default look, so this was refreshing….so now I’m sporting "Green Sky." 
Keep in mind that Google is rolling this out slowly to users, so if you still don’t see the option, just hang in there.