The GameSpy Technology Website announces that as of the end of next month, GameSpy owner Glu will discontinue backend services for games using GameSpy technology (thanks Joao). Word is: Effective May 31, 2014, GameSpy will cease providing all hosted services for all games still using GameSpy. If you have any questions about how this impacts your favorite title please contact the game's publisher for more information. Thanks for a great ride!" This will impact lots of games, and in one case, there's already a post on the Bohemia Interactive forums saying they are working on an alternatives for Arma 3 and Arma 2: Operation Arrowhead, while users of their older games will just have to get by without the services GameSpy was previously providing:

Important notice: effective May 31, 2014, Gamespy will cease providing all hosted services for all games.

This is going to affect multiplayer in our games that use Gamespy for matchmaking, cd keys authentification and NAT traversal from Arma: Resistance to Arma 3. We are planning to introduce an alternative solution using Steam to Arma 2: Operation Arrowhead and Arma 3 users.

Other games (Take On Helicopters, Arma 2, Arma 2: Free, Arma, Arma: Cold War Assault) will have more limited multiplayer experience with loss of server browser, cd key authentification and NAT traversal systems. That said, direct IP connection to servers should work even after Gamespy services are no longer available.

We apologize for any inconvenience.