Finally, there is a huge work on Wiki (manual) as well.
What's next? Most likely we'll separate a branch for mentioned LINQ updates and bugfixes to release it as v4.0.3, and start working on sync & caches - there will be ~ 3.5 weeks to implement them, and I hope this will be enough.
Personally I'll be spending most of my time here - telling you about features and internals of DO4, as well as work on docs and marketing related stuff. Finally, there is a time for this ;)
P.S. We're going to publish a survey about "post-sync" features shortly - please pay attention and fill it, we'll decide what to do next by its results.