From the home page:

August 20, 2007

Stella release 2.4 for Linux, Mac OSX and Windows is now available. Ports to other operating systems will be released as they become available. A partial list of features is:

* Added new video sub-system where fullscreen and windowed modes are treated differently. Windowed modes now use '-zoom_tia' and '-zoom_ui' arguments, while fullscreen modes can be specified by resolution using the new '-fullres' argument.
* Widescreen video modes are now supported; Stella will simply center the image with surrounding black borders.
* Many UI-related changes, including resizable ROM launcher and debugger windows, and a new UI palette (the previous 'classic' palette is still available). This is still a work in progress.
* The locations of all major config files (statedir, palette file, cheat file, properties file, etc) are now configurable from the commandline and within the UI.
* Updates to TIA palette support. Added SECAM support, and removed the built-in 'original' palette. Standard, z26, and user are still available.
* Various bugfixes to some debugger commands. The 'run' command no longer causes a crash, and several others have better error-checking.
* Added more complete cartridge auto-detection for Commavid (CV), 3E, 3F and Activision (FE) formats.
* Removed XStart and Width ROM properties, since the forthcoming TIA rework won't be using them.
* Reworked internal storage of ROM properties to be faster and take up less space.
* Added several different ways of stretching the OpenGL image to the '-gl_fsmax' argument, for more flexibility.
* Removed OpenGL aspect ratio setting favour of the previously mentioned video changes. We'll see how this goes.
* Removed dirty-rect support from software rendering, since it was actually sub-optimal in Windows and OSX and defaulted to off in previous versions.
* Added support for gzipped ROMs.
* Re-added pause support.
* Re-added support for Windows 98.
* Removed support for 'STELLA_BASEDIR' environment variable, since each config file can be now configured separately.
* Removed '-fastscbios' argument, since it must always be turned on.
* Removed PSP support, since it hasn't been updated in over a year, and someone else is maintaining another port elsewhere.
* For the Unix/Linux port; fixed 'make install' issues, and changed icon to PNG format.

Have Fun!