CMS w/ MySpace-like user editable profile w/ CSS/HTML?

Is there a module for a content management system or any kind of web software that has support for user's putting CSS tag edits and HTML code into their profile responses? If not, what do you think would be the best CMS to use as a development platform for a social networking website with this feature?

I read a reference to a Durpal module that seemed to say that it would not only do this (profiles w/ HTML/CSS), it would somehow also interpret a user's PHP code as well; but the reference wasn't clear and I can't find the module. If allowing user's to insert HTML is dangerous for security then giving them access to PHP would really be a can of worms. I am intimidated in approaching this project by my lack of knowledge of what sort of security issues HTML & CSS user editing would introduce. I suppose Wikis have to deal with somewhat similar issues.