It is currently uncertain if Siri will be available, if it goes past the early testing stages, in OS X 10.9 for all users. Siri on iOS devices is tied specifically to certain, newer iPhones, iPads, and iPod touches, so it is possible that Apple will make a similar decision for Siri on the Mac. However, Dictation, which uses a similar infrastructure and hardware resources as Siri, is available on all Macs capable of running Mountain Lion, the current Mac operating system that introduced Dictation.
Notably, Maps is being included as a framework for developers (ie. MapKit) which means developers will be able to utilize the service for applications submitted to the Mac App Store. It's unclear if Apple will be including a standalone Maps application in the new OS.
OS X 10.9 is expected to launch around July of next year.