Wiki functionality is offered as a tool within the context of any community by using the Sharebox or from the community wiki tool. Wikis promote meaningful topic associations between different pages.
Wiki page creation is simplified, but full SharePoint functionality is always available.
Wiki authors can decide which page they want to act as a root to their wiki by moving it on the top of the wiki tree. And reorder the wiki pages dragging and dropping them on the wiki tree.
Wiki page authors can create links with other wiki pages by relating them during the page creation.