I got several (more and more) questions around HP OneView and existing Virtual Connect domains. Is it actually supported or not? Can it be done online? What about VCEM? Stacked enclosures?

Well I want to point for this kind of information to a great document that HP published recently:
Transitioning a Virtual Connect Configuration to HP OneView

The document explains what is currently supported and what is not supported. Also be aware that today it is not possible to migrate online from a currently active environment to a Oneview managed place. Downtime will need to be planned all the time since the server profiles need to be (re-)created inside HP Oneview.

The document describes a way how HP tries to make your life a bit easier in achieving all this, for instance when you want to obtain virtual MAC and WWN addresses.

I assume in upcoming versions some changes/enhancements will be made to automate this more but it is good to see that these kind of whitepapers are shared just after release of this new product.