Eh, it's Apple's in any meaningful way. The project is led by Apple's Laurent Sansonetti, hosted by Apple's Mac OS Forge, and Sansonetti has said that MacRuby is intended to replace RubyCocoa, which is currently bundled with Mac OS X. MacRuby also recently started making improvements to Apple's BridgeSupport framework. I don't know how much more an open-source project like MacRuby could do to deserve to be called "Apple's."
MacRuby is a free software project by Apple Inc. Many folks inside and outside of Apple contribute to this great project and we have a MacRuby Project Team page to list them. Please feel free to contact us if you have any questions, ideas or bugs to report.
