Michael Gray has composed a post that helps SEOs find out which pages of their site haven't been crawled, which becomes increasingly more important due to Google's removal of the supplemental index. He explains that you should put a timestamp on every single page, after which you wait about 2 months. At that point, you can perform a search for the article plus the date and you should get your results.
Michael then explains how you can optimize those pages to have them become crawled and provides other informative insights as well.
Is it worth the hassle? It depends on how important this is to you. The goal should be to integrate code into the page so that you don't have to manually add timestamps to every single page. Still, if it is important to you and you want to know (but don't have the resources available to code it in the footer), it may be worth the effort to do it.
Forum discussion continues at Sphinn.