I had a 2006 Core2Duo 15" MacBookPro before and the screen on that became dim. Did the 2006 MBPs have CCFL backlights??
Yes.
LED backlights weren't until the 2007/Santa Rosa MacBook Pro line (with a couple exceptions: the 2008 17" MacBook Pro came with LED backlighting only if you ordered the 1920x1080 screen upgrade; the lower-resolution 17" screens still used CCFL, both in 2007 and 2008.)
In the MacBook (non-Pro) line, only the very last plastic MacBook, along with the Aluminum MacBook came with LED backlights.
For the iMac, it wasn't until the 2009 model that LED backlighting was used. (And then only on the 27", the 21.5" model didn't get LED until the 2010 model.)
The MacBook Air had LEDs from the initial model.