Apple may be integrating Siri and Maps into the next version of Apple's Mac operating system, OS X 10.9. According to 9to5Mac, early testing builds of the software include Siri voice software and a version of Maps based on Apple's controversial mapping software for iOS. So far, it looks like Maps for OS X may only be available to developers, who can use the API to include maps within their apps sold through the Mac App Store.
Apple's last major OS release, Mountain Lion, integrated a slew of iOS features like Notification Center, AirPlay, iMessage, Dictation, Reminders, Notes, Game Center, and iCloud, so it's no surprise to see the company move to further homogenize its software offerings. Apple released a preview of Mountain Lion in February and announced its commitment to a yearly update schedule, so we can expect more solid information on OS X 10.9 sometime early next year. However, we're still likely several months away from seeing OS X 10.9 in action, so of course these features may change or be removed entirely before then.