According to sources very familiar with Apple displays and MacBook development, there is no discernible difference between CCFL MacBook Pro displays and the new LED MacBook Pro displays. All the eyeball tests so far have been either faulty or just plain wrong.
Think about it for a sec. If Apple's displays were even 5% brighter now than before, don't you think that'd be one of their selling points? They're a company known for picking the "optimum" (some would say misleading) test results and figures and using that as something to boast about.
If you wanted to make a slightly more scientific test between the two displays, here's how.
First, you need to give CCFL displays a half hour to warm up to full brightness. Then, turn plug both MacBook Pros in and turn them up to full brightness. You'll need two "new" laptops as well—that 6 month old laptop you got for Christmas won't make for an accurate assessment.
A couple more things to note. The best way to test the displays are to calibrate them with an external device. Also, the LED display can run at very low brightnesses, but the CCFL one can't. That's why 50% brightness on LEDs is not as bright as 50% on CCFLs.
Then again, Apple may want to save their "it's brighter!" selling point for a case when it's 30% or 50% brighter than the previous generation. Saying it now and having people not be able to tell that it's brighter kind of hurts their rep.