I don't know how exactly it all comes together, but I would hope that Maloader and Cocotron (http://www.cocotron.org/) would enable many Cocoa apps to run on Linux (on Intel) without recompilation.
From the Cocotron website: "The Cocotron is an open source project which aims to implement a cross-platform Objective-C API similar to that described by Apple Inc.'s Cocoa documentation. This includes the AppKit, Foundation, Objective-C runtime and support APIs such as CoreGraphics and CoreFoundation."
From the Cocotron website: "The Cocotron is an open source project which aims to implement a cross-platform Objective-C API similar to that described by Apple Inc.'s Cocoa documentation. This includes the AppKit, Foundation, Objective-C runtime and support APIs such as CoreGraphics and CoreFoundation."