Great summary, thanks for taking the time!
Keep in mind the figure (and I hesitate to call it a fact, but it does seem reasonable) that 70-80% of Canon lenses are produced in Taiwan. That means more than 70% of lenses Canon makes comprise the EF-S 18-55mm, EF-S 55-250mm, EF 50mm f/1.8 II, and EF 75-300mm's. I'd venture a guess that the margin on L lenses is higher, but like the Rebel bodies, the >$300 lenses are the core of Canon's dSLR business. The high end gear (L lenses and xD bodies) don't generate the same level of profit...at least direct profit. But, the Canon gear in the hands of pros - at sporting events, shooting your wedding or portraits, etc., that's advertising for Canon. That leads to stronger consumer sales or Rebels and EF-S lenses, which in turn funds the next round of R&D for xD bodies and L lenses.
The DSLR Camera, Lens, and Accessory value to Canon continues to grow, In their latest Financial Report, the consumer FY 2011 projection is for 23% of their volume on a unit basis to be DSLR, lenses and accessories, and in income value, 69%.