Hello
We just released free version for vBulletin 4.0.
It is still in beta stage. It wasn't tested with vBSEO 3.5 yet. We will cover this in next release
We released this free version early, because many people was asking about it and to get experience for paid version integration
So enjoy
You will find it here:
vBET 2.4.x - free version for vBulletin 4.0