Say what you want about ergonomics, lens availability, etc, but I think one area in which Canon has lagged behind other companies is in their sensor designs. Canon has been using essentially the same sensor since the 7D, which is two years old now. Meanwhile, Sony's APS-C sensors (also used in Nikon and Pentax DSLRs) have totally turned the tables around. They've gone from playing catch-up to completely surpassing Canon's formerly legendary CMOS sensor design.
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Here, you can see just how much better the D7000 is with its Sony sensor. Other cameras using a similar sensor (such as the Sony A580 and Pentax K5) perform nearly identically to the D7000.
Even the Sony A55, with the 1/3-2/3 stop light loss inherent to the translucent mirror, easily beats the T3i (which is Canon's newest camera, and yet does not really improve on image quality at all).
Here's to hoping that Canon can deliver something better for 2011