According to the CV of BioWare employee Rob Bartel, the developer is working on an "unannounced multiplatform action title".
During his time with the project, Bartel was "Principal Designer, Lead Multiplayer Designer - Unannounced multiplatform action title at BioWare EA".
He's now listing himself as "Principle Designer at Bioware EA".
Previously, BioWare boss Ray Muzkya did mention he would like to see future Mass Effect and Dragon Age titles get co-op.
ME3 campaign online co-op ftw, etc.