Stephen Reid announced that BioWare will host a by-invitation-only hands-on gameplay event on April 5th in London. The event is free, but you must be a member of the official forums and send an email to request an invitation to either the 7 pm or 9 pm session. You must follow some very specific instructions, so be sure to go to the official forums thread for all the details.
All approved guests will be notified by Thursday, March 31st. You must be 18 or older to attend.