Bioware has confirmed that they will release a demo of Mass Effect 3 in January 2012 that will contain both multiplayer and single player components. Jessica Merizan, Community and Social Manager at Bioware released a FAQ regarding the upcoming demo.
What are the details of the Mass Effect 3 pre-release demo?
•The Mass Effect 3 pre-release demo will launch in January 2012 (exact date TBA).
•The demo will include both single-player and multi-player sections.
•The demo will be released in all regions where the game is
How can I get early access to the multi-player portion of the Mass Effect 3 demo coming in January 2012?
•Owners of Battlefield 3, on any platform, who activate their Online Pass will automatically be granted early access to the multiplayer portion of the Mass Effect 3 demo. There is no need to enter any other codes, the early access will be applied to the EA Account associated with the Online Pass. Note: BF3 Origin Customers automatically have the BF3 Online Pass.
•This applies to all regions where the demo is released (to be announced)
•The exact date of the demo launch will be announced in late November
•There will be another program whereby players and fans of the Mass Effect franchise can unlock this early access (with no purchase necessary) – this will also be announced in late November or early December.
•There will also be a tool posted on www.masseffect.com allowing players to check if their EA account has been granted the early access.
•The length of the early access period is TBA.
•The single-player section of the demo will be available to all players on day one of the demo launch.
Mass Effect 3 is still on track to release on March 6, 2012 in North America and on March 9 in Europe for the Xbox 360, PlayStation 3 and PC.
Source: Bioware Forums