Its a link at the top of the page, and I find it handy, rather than individually clicking all boards, if you want to just get up to date. You can also try viewing active topics if you'd prefer. View new posts just says new posts that have been made since your last visit.
If you can't find the link, try this:http://wikipediareview.com/index.php?act=Search&CODE=getnew
It'll redirect to a generated page that displays new threads.