Where do you see that @transaction.atomic is deprecated? It's not in the release notes[1] and if I recall correctly, was only introduced in 1.6 as a means to come up with a consistent API for nested transactions and savepoints. Are you implying that it's deprecated as a decorator? Even if that's the case, I still can't find a source.
That said, there seems to be a slight hiccup in third-party apps moving towards 1.7, since those that have existing South migrations are in the dilemma of whether to break backwards compatibility in moving to the native migrations framework. Also there is a nice chunk of deprecated APIs (such as @transaction.atomic) that many projects will throw warnings about now, until those are patched.
Personaly, I've already started migrating projects to 1.7 in anticipation of an upcoming release in the next few weeks.
Kudos!