The first one allows you to capture burst shots of a group of people and then automatically chooses the best one judging by face expressions, while the second allows you to capture fast-moving objects improving shooting speed. The other two are quite self-explanatory, and were available to customers of lower end Nokia phones via third party applications, with the Self Timer being a preloaded feature on various phones.
For now only users in China and the United States will get the update. Updates to other countries will follow later in July. Head to the 'Windows Phone Marketplace' to get the juicy app now.