I don't have permission yet to create a blog post in this forum but wanted to alert you to a couple of blog posts I recently wrote.
The first post has a basic overview of the Cinder block storage service in OpenStack.
Laying Cinder Block (Volumes) In OpenStack, Part 1: The Basics
The second post has details on how vSphere uniquely integrates with Cinder:
Laying Cinder Block (Volumes) In OpenStack, Part 2: Integration With vSphere