I had a tip from a person who has sent some reliable info in the past saying that the Canon lenses delayed due the Japan earthquake might arrive as early as May 2011.
See this post for news about the delay: http://www.photographybay.com/2010/11/02/canon-delays-ef-8-15mm-300mm-and-400mm-lenses/
That, in fact, the production is not the problem, but rather the shipping of the lenses is where the hold up is at. Because of the blocked roads near the plants, Canon can't get the lenses out. The lenses are expected to ship out soon though and arrive in the US in May.