The first look at Book of Vile Darkness concerns campaign themes and an arc that will hopefully unify an evil party to work together long enough to see results. Staples such as conquest and destroying the world are present, along with working against other evil forces and killing gods. Running an evil campaign can be a tricky business, and in my experience players tend to use it as an excuse to wreak havoc without any direction. Kind of like Chaotic Neutral, except that there might be more murder depending on your groups definition.
There is not a lot of information, and hopefully these concepts are expanded upon. At the least I hope that it offers better stuff than a bunch of weak-ass feats and prestige classes that we got from the original Book of Vile Darkness.