Members have probably seen that "WHAT'S NEW" on the main menu now provides the new "Activity Stream".
If you liked the older version of What's New, it is still available to you as 'new posts'. Accessible from the site Home Page, down the left hand side, under your avatar, and it is also on the AP extra's menu as the first item.
If you click into your profile, you will also find a new tab 'My Activity'. This shows your own posts and replies to threads you have already posted in.