The next version of WordPress, version 3.1 (currently in beta) will feature internal linking, or the ability to search through site content and insert post and page links directly in the editor. WordPress developer Alex King, in response to this upcoming feature, has released a new plugin called Internal Link Shortcode.
King describes the plugin’s function:
My plugin provides a way to create internal links via shortcode so that they will always remain up to date if the page/post titles are updated or the URLs are changed. For some folks, this feature is pretty important. Like the built-in feature, there is a nice type-ahead search to allow you to easily find the post/page you wish to link to.