Text, yes, but not images (or at least, that's how it should be). The strong majority of images are fully copyrighted and haven't been released under a free license; they should either be tagged as being used under fair use, or deleted if the wiki's policy is to only accept free images (which wouldn't make sense, considering that the nature of most articles requires copyrighted images, such as website screenshots, logos, etc.).

Pretty much every wiki runs this way; their text is freely licensed, but images are independently licensed as needed.