Slowly but surely, Apple seems to be adding new features to its latest iteration of AppleTV that differentiate it from its older, nearly identical model. Until recently, any new additions and updates rolled out without prejudice between the 2nd and 3rd gen AppleTV models.
However, with the release of iOS 8 last week, only owners of the 3rd gen AppleTV saw the refreshed UI and integrated Beats Music app. Additionally, it was learned today that only owners of the refreshed 3rd gen Apple TV (model #A1469) will gain the ability to use peer-to-peer AirPlay, which allows those on iOS 8 and OS X Yosemite to transmit content to an AppleTV without first connecting to the same wireless network.
As time goes on, I can see owners of 2nd gen AppleTV models being enticed to upgrade to newer models if this trend continues. As an owner of an older, well loved 2nd gen, I have long enjoyed the symmetrical update system. May well be time for an upgrade.