What is the real native maximum resolution of mid–2010 iMac's iSight camera?

I think it's 1280x1024, as that's what the LED backlit MacBook Pro's and onwards used. The Lion version of Photo Booth uses the max resolution and crops it.

720x480 is actually a standard resolution - it's what most DVD's use.

Some discussion sources report that using QuickTime video capture at the stated maximum quality. That would hint my built-in iSight's resolution is in fact 1280×1024.

Moreover, the iSight upgrade (from 0.3 to 1.3 megapixels) has been noted first at Mac Daddy World and later re-reported at TUAW and Engadget:

• The product ID for the 0.3 MP iSight is 0x8501 and its vendor is Micron…
• …while the 1.3 MP iSight's product ID is 0x8502 and the vendor is Apple.

Looking at my System information report, I can confirm the product ID is 0x8502.

So, summa summarum: mid–2010 iMac's built-in iSight camera has a native resolution of 1280×1024 pixels.