Can I use WordPress logo?

Hi everybody,
I’m making the logo for my websyte. It is based on WordPress mu platform and it will offer to users a free wordpress blog.
In the middle of the name of my site there is a “W” letter… To design that letter i would like to use the wordpress logo’s “W” (the one drawn with a circle around) to let people understand that the blog they get is based on WordPress.
Can i do that?

Thanks