In this article Jeff reviews the Logical Class Diagram and the Sequence Diagram.
My favorite bit:
The benefit of the revamped diagrams is that not only can the represented information be semantic, but it can also be non-semantic. That is, it can be used to communicate ideas and thoughts without adding any particular constraints to a solution. This makes the new suite of diagrams in the Architecture Edition particularly powerful and useful.
Hopefully Jeff will cover more in his upcoming articles.