Yes, that is true.
However, I see that AMD will soon launch the Phenom II line of laptop processors, with triple and quad-core options. And the quad-core offerings will have a lower TDP than Intel's. A Phenom II X4 P920 1.6 GHz will consume only 25W and could replace the Core 2 Duo P series which equip the low-end MacBooks. Apple could use the Phenom II X4 N930 2 GHz (35W) to equip MacBook Pros. I don't know yet the performance of these mobile processors, but they are quad core chips and, at least in desktops, AMD quad-core processors seem to offer better performance than Intel dual-core processors with HyperThreading.
If Apple is considering AMD processors, it is certainly not looking at its current line-up.
The current iMacs are great value because of the LED-backlit IPS 27" screen, but they are far from being cheap machines (i.e. it is worth it, but it's still a lot of dollars).
Anyway, my point is: Intel chips are better, indeed, but a transition to AMD doesn't necessarily mean a downgrade. I am talking specifics here, not in general. Apple uses mid-range Intel processors, and AMD may be able to offer that.
I mean, Apple is never going to put a US$ 999 six-core Core i7-980X 3.33 GHz inside a US$ 1,999 iMac (which current has a Core i5-750). But it may put a US$ 195 six-core Phenom II X6 T1055 2.8 GHz, because it will cost the same as a Core i5. If the performance of the T1055 is superior to the performance of the Core i5, that would be a great change. This would be an upgrade, at least for me.