I honestly don't see why not. Apple specified an official limit of 4GB for both the 2.4 and 2.53; and they were both released at the exact same time. The only differences are the CPU speed, GPU memory, installed RAM and hard disk size and none of those should have any impact on supported RAM. And I don't see why Apple would bother to keep the firmware for the two logic boards different.
So assuming this is indeed a late '08 MBP that has 8GB of RAM working and is working well, I'd say that theoretically, 2.4GHz owners should have reason to celebrate too.
Apple originally listed 2.4GHz as not possible for 8GB ram. Not sure if that's changed. The 2.53GHz randomly showed up as 8GB capable on Apple's upgrade parts site but there was speculation to which revision it referred to.
I found a app called rember, http://www.kelleycomputing.net/rember/, which runs memtest which is a app that runs a bunch of test to test and find problems with your memory. Thought I would download and try it out and see what it does. So I ran it and opened activity monitor to see how much ram it was using. Activity Monitor reported 7.98gb of ram being used, memtest using 6.05gb. System stayed very stable and very responsive. Below is a screen capture of Activity Monitor from grab showing 7.98gb ram being used.
I would like more info on piggy app please before I ask someone to send it to me and run it on my system.
Piggy is unnecessary since the Rember program clearly shows that you were able to execute more than the 4GB ram barrier that was originally established. Now the question remains is that, is it because the 64-bit kernel allowed this or does the kernel not matter and it's the firmware?