YouTalkingToMe - 3:54 pm on Apr 26, 2010 (gmt 0)

Therefore, as MSIE usage has declined from 68% to 51% on my site over the last 3 years

I can agree with you about MSIE usage decline. I see similar numbers on our GA accounts.

People using MSIE tend to have a significantly higher CTR on AdSense ads compared to visitors using any other browser.

That's not true for our websites. Both our CTR and eCPM are better for visitors using Chrome, Firefox and Safari (in this exact order) if compared to CTR and eCPM of visitors using MSIE.

However I'm a troll living in the jungle, so don't take it too seriously. ;-)