BioWare has announced that Mass Effect 3 will have a pre-release demo in January 2012. The Online Pass for Battlefield 3 will unlock this early access and there will be other ways to get involved announced sometime between late November and early December.

The demo will include both single-player and multiplayer sections. However, it seems the multi-player are the parts limited to those that unlock it through the Online Pass or other means – the single-player section of the demo will be available “on day one of the demo launch.”

Source: www.bioware.com