Yes they are adding the functionality for backgrounding tasks etc.. I've heard and seen nothing on the "sharing" of between applications, only of adding in 3rd party handlers for mime-types. (ie.. opening an ODF in a 3rd party ODF application from the stock mail app). That does not require any rewrite of permissions.
And the way that the new backgrounding is being added is fairly seamless and doesn't require much of any change at all. And no "completely different programming paradigm" is required. Not sure who you are talking with, but they don't seem that well informed. All Apple did was pull in the "closures" that they introduced in Mac OS X 10.6 to build the "background tasks".. not really a "completely different" programming paradigm.
And I do believe that the whole "different frameworks" mess is just Apple and Adobe getting into a "pissing contest". Apple, Adobe, and Google are all acting like little kids in a playground up there and causing lots of collateral damage down here for the rest of us.