There is not a last 40 feature but the forums do allow several advanced searches and views by days. At the bottom of every main forum page you will see a "from" drop down box. You can choose to view posts anywere from 1 day ago all the way to the beginning and everything in between. If you click search you can also specify the dates to look through if you are looking for keywords. You may also view the last 5 active posts on the home page in the right hand menu adjacent to the users online information. Last but not least and probably the easiest last posts feature to use is the "view new posts" button at the top of the forums home page. If you click this you are going to be shown everyhting you have not viewed no matter how long it has been since you last visited.
The boards allow many more advanced features as well. It would be a good idea to check the FAQ by clicking the FAQ button at the top of the forums pages to get some more ideas of the things you can do with this new system
Note: To use these features you will need to go into your user cp (button at the top of the forum pages) and select to use cookies and auto login. Just click those two radio buttons and then save. You need the cookies to track the new posts.