The first draft of the Messaging chapter is complete, meaning that the chapter is finished ... for now. (There will always be changes in the future, and each of the first three chapters, in particular, will need to have all their screenshots retaken.)
The first draft version of the Messaging chapter is Messaging 0.5. I'll move along to other content before going back and cleaning up this and other first draft chapters. It's likely that I'll start cherry-picking parts of chapters for a while, but now that Windows Phone 8 is out in the world, there are no issues with regards to what I can write about.