As Grigori has already mentioned, we (the Enterprise Library 4 team) are working on a new Dependency Injection block, named Unity. Grigori's post gives some of the details of our API. The existing API covers probably the 80% case, and we've got an extensibility story for those who need the container to do more.
Underlying our container implementation is the ObjectBuilder library. As I've mentioned before, there's a general impression that OB isn't very good. In asking people, most actually say "well, I had no idea where to start so I gave up." This tells me the real problems are discoverability and documentation. We can't do much about discoverability at this point. After all, I'm working on the container to hide all that stuff away! But if you want to extend Unity, you'll need to understand ObjectuBuilder. That, hopefully, I can help with.
About six months ago, I got kind of fed up with OB. Or more specifically, fed up with myself for not understanding it. So, I set out to understand this library and write down my discoveries. The result is an (at this time) incomplete document called Deconstructing ObjectBuilder. Over the next couple of weeks I'll be posting that document here along with example code. Something like it will also form a chunk of the docs for Unity, but I wanted to get it out there in it's original form.
I hope you all find this useful. At least this way now I won't have to keep mailing Word docs to people.