The top menu has been removed from the main page.  This way it looks like the left menu has been re-ordered for the remaining pages.

The Most Active Threads link in the menus now actually lists the most active threads, assuming there are any.  Previously, it was just a header for the items underneath, but now details of recently-active threads are listed in the Forums Main Page.

The most active threads are calculated diferently, too.  Formerly...

SELECT t.title, t.id, COUNT(p.id) AS postCount
FROM threads t LEFT JOIN posts p ON t.id = p.threadId
WHERE p.date > ".(time()-(60*60*24*14))."
GROUP BY t.id
ORDER BY postCount DESC, t.title
LIMIT 0, 5;

In English: the top five threads with the most threads in the past two weeks, in descending order.  This has now become...

SELECT t.title, t.id, AVG(p.date) AS averageDate
FROM threads t LEFT JOIN posts p ON t.id = p.threadId
GROUP BY t.id
ORDER BY averageDate DESC
LIMIT 0, 5;

In English: the top five threads with the highest average date, in descending order.