The latest retail patch is v1.02; digital distribution versions already include this.
An unofficial port of Freespace 2 is available here. The installer and the source code of the port itself is available. Keep in mind that the installer is not compatible with GOTY/Sim and non-english version.
FS2Open is an open source port for Windows, OS X and Linux. It features improved graphics, mod support, mutli-platform support, improved mission scripting, lua scripting, optimizations, and various bug fixes.
Improved Graphics: FSO adds shader support to the Freespace's rendering pipeline to implement soft particles and other effects. Support for Normal Mapping, Environment Mapping, Glow Mapping, Skyboxes and soft shadows have been added.
Mod Support: Mods can now be installed and read without altering game files. Only a launcher is required to implement an installed mod, and multiple mods can be installed within the Freespace directory.
Multi-platform support: FSO enables Freespace to be run in Windows, OS X, Linux, and (experimentally) in FreeBSD. Multi-platform compatibility is maintained on all stable FSO releases.
Mission Scripting: FSO more than doubles the available functions (known as SEXPs) that can be used in mission creation, including in-game cutscene controls. It also allows the mission creator to disable Briefings and Debriefings or add Fictional text to the mission.
Lua Scripting: Lua scripting has been added to accomplish things that the regular functions cannot and also alter the state of the game outside of missions.
Optimizations: The FSO engine has been optimized to make more complex models and textures usable and improve CPU performance.
Bug Fixes: Since the beginning of the FSO Source Code Project (FSOSCP), over 2000 bugs have been reviewed and fixed or explained.
Community Support for FSOpen (FSO) can be found at Hard-light Productions
FS2Open helps install various popular mods including a port of Descent: FreeSpace – The Great War.
Active development of mods can be found at Hard-Light Productions