JavaScript as an alternative to AppleScript on OS X Yosemite
AppleScript contains some amazingly powerful APIs, but is nearly impossible to write.  Having a Javascript (successor?) implementation is going to unleash its full potential.  I could see it becoming much more widely used and supported by third party apps.  This is wonderful.<p>In the same cycle that they release a brand new language, they begin the deprecation process for their (only?) other proprietary programming language in favor of an existing language.  Pretty cool.