"Hi, my name is Samantha. I am an english/american voice"
Anyway the issue with Siri integration on the mac is due to the microphone.
I believe now the late 2013 and up model have dual microphones that now would be possibly allow Siri to work properly. I'm guessing the follow up to Yosemite may have Siri but may be only for select models with dual microphones.
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Here's the article on the microphone issue with siri integration on the mac...
http://www.wired.com/2012/02/no-siri-mountain-lion/