watchOS 2 is of course the new firmware for the Apple Watch.
When the Apple Watch was released with the first watchOS, folks all around complained that there weren't enough watchfaces on the device. watchOS 2 brings in two new watchfaces, support for third-party complications, and much more.
The two new watchfaces are Photo Album and Time-Lapse. Photo album allows folks to set a different photo to show up behind the clock, each time a user checks the time. The face was seen in Apple's earlier Watch marketing materials, but wasn't there when the device released. The second face is called Time-Lapse, featuring time-lapse photography posted online, like sunsets and clouds above a city, along with many more.