One way to get to another person's threads - hover the mouse over the name in the thread and notice a small link at the bottom called [NAME]'s threads on the lower left corner of the Profile card.
 
The other way is to click Browse Forum Users on the right of the forum page, and then click the link on the right for their # of threads.
 

Source

This article is based on this forums thread: http://social.msdn.microsoft.com/Forums/en-US/reportabug/thread/b0331a9e-8f23-4ea8-b728-b4b95f57ae32