Go to https://mail.google.com/mail/#settings/themes and choose!

https://lh3.googleusercontent.com/-lvO3xzvKaI8/Tg0OjdnGIbI/AAAAAAAAZ8Q/M-f4QCV4i8Y/s912/Capture+d%25E2%2580%2599e%25CC%2581cran+2011-06-30+a%25CC%2580+20.01.10.png

I like it, but drop the CapsLock on the buttons.

Now with ads at the bottom,

http://www.websonic.nl/nieuws/wp-content/uploads/2011/07/gmail_ad_bottom.jpg

Not seeing adverts here.
Not too fussed if they put ads at the bottom really, the ads at the moment I manage to successfully ignore :P Would be annoying if they added them at the top (or made Web Clips mandatory)