Update [June 07, 2017]: The update featuring the Notification Dots from Android O is now available under stable release too. So, you no longer need to install beta version of the launcher to get that cool feature from Android O. Get the stable version of Nova Launcher here.
Nova Launcher in its latest update to the Beta version (5.2 Beta 1) introduces Notification dots similar to the Android O. However, unlike Android O where long pressing the icon gives options to handle the notification, it is currently missing in Nova Launcher. Don’t shun them yet, it’s a beta version and they just introduced the dots. So, yeah.. let’s wait for the full-fledged Android O style notification badges.
Moreover, they recently introduced dynamic badges as well in the stable update that shows the profile picture of the sender on the notification badge.
That said, the latest update also introduces round search bar style (picture above) that can be activated by going into Nova Launcher settings followed by Desktop option and finally Search bar style.
Finally, there are some performance improvements and bug fixes for Android O.