Two new features have been added which most people will never notice. The first is when a new user signs up there us now a Captcha. This is needed for another upgrade which is being worked on but seemed like a good place to test out the code and see how it runs.
The other upgrade which will help people on slower internet connections (and overall server bandwidth) is the automatic sizing if photos. When you went to a page which had photo on it in the past it would download the entire photo then display the photo at the right size by shrinking it on your computer. Now the server shrinks the photo to the proper size and then loads it on your computer. So pages with photos will now load quicker.