Besides being the branding for Eloqua, I thought it would be helpful to clarify exactly what is currently part of The Oracle Marketing Cloud (Aug 13, 2014). It is actually not nearly as confusing as you might think!
There are four products:
#1. Eloqua (B2B Marketing Automation - you might have heard of it ) - link.
#2. Responsys (B2C High volume email centric marketing tool) - link.
#3. Compendium - (Content oriented tool used for collaboration and to help marketing leverage sales generated content - currently being integrated into Eloqua and Responsys) - link.
#4. BlueKai (Big data ad network tool - allows you to more accurate profile anonymous top of funnel traffic based on their interests) - link.
Worth Noting: All four of these products are going to be showcased through a distinct and dedicated Oracle Marketing Cloud track at Oracle OpenWorld this year Sept 28th-Oct 2nd.