In the main discussion page the "more recent threads" link in the "Recently accessed posts" portlet just repeats the last n threads so you keep getting the same set of links.
Hi Aaron -
When you click on "more recent threads" it sends you to the main recent thread page. You will see a "Page 1 of X" on the right hand side. You can use that navigation to get older-recent threads. You are right that if you click on "more recent threads" again from there, it just takes you tot he same page. Really that portlet shouldn't show if you are on the recent threads page already.