The recent news that GameSpy's servers would shortly be shutting down brought with it a huge list of games on a variety of platforms that would be affected.
Some games are just going to be quietly left die -- more than 50 EA titles are going offline at the end of next month, for example, as EA generally isn't in the habit of keeping old games' servers up and running for long -- while others have seen passionate fans and organizations working together to save the multiplayer modes of classic games.
The PC incarnations of the original Halo (Halo PC and expansion Halo Custom Edition) have been more blessed than most, however: Roger Wolfson, a developer from Bungie, is helping out a small team of fans in their efforts to keep the game's multiplayer servers up and running even after GameSpy's servers shutdown.
Halo's use of GameSpy was primarily through the GameSpy Master Server, which provided a centralized list of other servers for players to jump into Halo games on -- kind of like how Steam works with many popular online titles. Last week, online multiplayer service GameRanger announced that it would be adding support for Halo through its service, but the work Wolfson and the rest of the team are working on will see a new, official update to Halo's PC versions that features integrated lobbies and matchmaking.
The update is positioned as a maintenance release just to keep the game up and running rather than adding major new features to the game -- but it does also add support for resolutions up to 4800x3600, video cards with 2GB or more of VRAM and a number of smaller fixes. It will not, at present, work with any mods.
GameSpy is set to shut down on May 31. There's no estimated release date on the update as yet -- "soon" is the best we've got so far -- but you can download and try an early version from this thread, including support for dedicated servers.