The great new feature appears as Linked From in the Web Crawl overview (see image) which pinpoints the page(s) which link to a non-existent page. Read more >
By inserting a piece of JavaScript code which can be accessed via Tools Enhance 404 Pages, it will allow you to embed a widget in your 404 page that helps your visitors find what they're looking for by providing suggestions based on the incorrect URL. Read more >