It seems everything between Mountain Lion and iOS 6 will work together nicely. The only problem is Mountain Lion comes out next month, and iOS 6 won't until this fall.
And likely as a result of that gap, Mountain Lion won't see any Facebook integration until then.
Apple billed Facebook integration into its ecosystem as a pretty big part of its keynote presentation at the Worldwide Developers Conference on Monday, but that won't arrive on the iPhone until iOS 6 does this fall. And now a banner on Apple's website says Facebook integration won't come to Mountain Lion until this fall either.
That comes as a surprise, seeing as the developer preview version of Mountain Lion that was released Monday already includes Facebook, and, according to 9 to 5 Mac, it works just fine.
The Apple-dedicated website speculates that the reason for the delay in adding Facebook to Mountain Lion may be due to the agreement Apple and Facebook reached for the integration, which could require it to launch on all of Apple's platforms at the same time.