Are there any serious plans for a new supersonic civilian aircraft? Since the retirement of the Concorde and the Tupolev Tu-144, there aren't any civilian airplanes (passengers carrier or business jet) flying supersonic. I heard that Dassault and SAAB had rather advanced studies on this topic but abandoned them due to various problems.

Does anyone have current references indicating that an aircraft manufacturer plans to develop a supersonic transport aircraft?
Aerion is planning a supersonic business jet which has a projected completion year of 2021:



Here's an article Forbes have written about it.