F-Script is a Smalltalk dialect for Mac OS X. Clearly, many in the Mac community are already aware of F-Script, since it won an Innovators Award in 2003. I’d imagine many are always aware of F-Script Anywhere, which allows you to attach F-Script to any Mac OS X program. I wasn’t aware of this until yesterday, so I just had to say “wow! that’s cool!”.
Speaking of the Mac OS X software architecture, Apple has an open source package called Core Foundation Lite, which provides a number of the base classes used in Cocoa development. I knew that Mac OS X’s kernel was open source, but I didn’t realize that some of the framework code was also open source. CFLite is still quite low-level, but it is a way to move some code between platforms.