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Not 100%

But in mail contacts and calendars you can add a twitter account.

I dont think FB has been integrated yet.
 
Facebook won’t be integrated in OS X until later this year when iOS 6 is released. At least that’s what I’ve been reading. The Facebook Developer preview plugin still works though if you need it now. I’ve installed it and had zero problems so far (touch wood!)

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Hmm hope theres another way to add facebook and twitter. I use outlook for my mail, contacts, and calendar.
 
Cant find an option in calendar nor address book to add a twitter account, and the mail app wont open unless i add an email account to it..
 
Is there another step needed to show the "Click to Tweet" button in Notification Center? I added my Twitter account in Preferences but the button is not appearing.
 
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