The roadmap has just been updated with the new features of BlogEngine.NET 1.2, which we plan on shipping in September. As you can see it has a lot of new features - some are standard blogging features and some are original BlogEngine.NET concepts.
The 1.2 release will be as well documented and simple to modify as the previous two versions. In fact, it will be even easier to modify due to the new extension model that let's everyone write extensions and hook them into the event model of BlogEngine.NET.
To take full advantage of the features provided in version 1.2 you might have to update your theme. It's only going to be one thing in one file that needs to change, but we have more precise info on that when we get closer to the release date.