After waiting for so long that it was beginning to become unclear what was old hats everyone got used to and what was bleeding-edge development-only features, a new official, stable version of ZDoom has been released. Compared to 2.5.0, the largest and most noteworthy changes would be the rewritten menu system (now with mouse support), the textured automap, the addition of 3D floors, and the new MIDI synthesizers. More information can be seen here and in the official release thread.

Also: there is an official GZDoom 1.6.0 too, but technical problems prevented Graf Zahl from updating his homepage. Here is a direct download link.