mGSTEP is an implementation of NeXT's OPENSTEP
specification which has evolved into Apple's Cocoa Objective-C frameworks.
Designed for use in embedded devices it includes GUI frameworks that provide support for X11 and direct rendering to the Linux frame buffer.
Development of mGSTEP has been minimal for more than 10 years.
Sporadic development has resulted in several releases to mitigate the effects of obsolesence which arise from changes to the GNU tools, Objective-C runtime and improvements in Apple's Cocoa. These natural trends along with the advent of ever more powerful embedded CPU's tend to diminish the value of developing with mGSTEP. Better maintained alternatives exist (see below) and are therefore well-advised for new projects.
mySTEP is a fork of mGSTEP that has been actively developed for many years as a platform for handheld mobile solutions.
GNUstep and Cocotron are the two most active Open Source projects which provide Cocoa compatibility. Both target a broad set of features and as a result they are more likely to provide compatibility with modern environements.
Cocotron is the basis for several Mac OS X applications ported to Windows.
GNUstep is a GNU project with a long development history and a wide variety of extensions.
mySTEP is developed for handheld mobile devices. Development snapshots are released periodically.