Back to the thread topic itself...
it suffices to say that Canon would like to get new technology to us as soon as economically possible. I was in Tokyo when the earthquake hit last year -- lots of damage to many manufacturers, to say the very least (not to mention the human toll.)
Lenses and camera are all on loose cycles. Those cycles are getting shorter with the fast rise of Nikon, who blitzed their lineup in 2007. Canon is beginning to react, it just takes time so let's be patient

Lens releases per year:
Nikon |
Canon (with specific models)
(6) 2011 (4): 500mm II; 600mm II; 18-55mm EF-S; 55-250mm EF-S
(9) 2010 (7): 300mm II; 400mm II; 8-15mm; 70-300m L; 1.4TC; 2.0TC; 70-200 II
(7) 2009 (5): 100mm Macro; 15-85mm EF-S; 18-135mm EF-S; 17mm TS; 24mm TS;
(7) 2008 (4): 24mm f/1.4 II; 18-200mm EF-S; 200mm f/2; 800mm
(7) 2007 (4): 16-35mm f/2.8; 14mm f/2.8 II; 55-250mm EF-S; 18-55mm EF-S
(4) 2006 (3): 70-200mm f/4 IS; 50mm f/1.2; 85mm f/1.2; 17-55mm EF-S;
(2) 2005 (4): 60mm EF-S; 24-105mm; 70-300mm IS; 18-55mm EF-S
(4) 2004 (4): 70-300mm DO IS; 28-300mm; 10-22mm EF-S; 17-85mm; 28-90mm