Per the NHC (see link below), for the period 1966-2009, the average date for 3rd named storm for the season to form in the Atlantic is August 13th.
http://www.nhc.noaa.gov/climo/
The season cancel posts will no doubt start by Wednesday if we don't see another system looking likely to develop...but can you really say 'seaon cancel' when the season doesn't start until Friday?

May 2012 has already made this season, or pre-season, memorable. We may very well go another month...or 2...before we get another named storm if we look at the climatology and season history. Even in 2005, we didn't see the C storm until July 3rd!!!
Date "C" storm has formed in the Atlantic by season:
2004 - August 9
2005 - July 3
2006 - July 31
2007 - July 30
2008 - July 18
2009 - August 16
2010 - August 2
2011 - July 20