From GNUstepWiki

Some definitions

• [mySTEP] is the GNUstep based GUI toolkit (i.e. frameworks) extended by QuantumSTEP (which adds an application suite e.g. for address book, calendar, mail, etc.) to develop applications for Linux/X11 based handheld devices (i.e. Sharp Zaurus, OpenMoko Phone)
• iPhone SDK is the Apple SDK to develop native applications for the iPhone and the iPod Touch

Comparison

	QuantumSTEP	iPhone SDK
Available for Developers	continuous progress since 2003 (mySTEP)	beta now, final June 2008
Foundation, AppKit, Small WebKit, PDFKit, IOBluetooth, X11Render, SQLite | Foundation, UIKit, WebKit, Core Audio, OpenAL, Core Animation, OpenGL, SQLite
free (cross-gcc, etc.) | free (by registration only)
not required (100% same source code) | included
Mac: Xcode 2.4 or later, Interface Builder, Xtoolchain Linux: Project Center, GORM coming | Intel Mac: Xcode 3.1, (Interface Builder coming), Linux: no
2.95.3 (with Obj-C 1.0) | 4.x (with Obj-C 2.0)
free and open as you like and need | only through „App Store“ at 99$-299$/year + revenue sharing
none, but www.gnustep.org | appears to be limited and US only
since 2003 (mySTEP for Zaurus) | Beta: now, finally June 2008
Sharp Zaurus, OpenMoko, Acer n30, more to come | iPhone, iPod Touch, (more to expect, e.g. Tablet?)
Interface Builder | Code (IB coming)
LGPL | NDA
none imposed by project | type of applications is restricted (i.e. no download of other executables)
10k ... 1 Mio | ca. 10 Mio
FSF GNUstep project, quantum-step.com | Apple