I think that for the sake of this being a contest, there's no need to
BUT considering this is a logo contest for a website, I also think it's a rather serious lack of professionalism to create a logo for someone's company or website that incorporates trademarked images from someone else. I mean, I don't see why you would even enter a logo like that... it's can't even be among the entries to be taken seriously.
And if you start a contest for a site logo, why would you ask for trademark elements to be included in it? You can make the logo and all... no big deal, but you would never be able to use it without risking getting a notice from Adobe.
So be nice people, but common sense would dictate that contests and such for logos and company style brandings should probably not have other trademarked images contained within.
Dan