32bit float really has nothing to do with an application being compiled as a 64bit application. The bit depth of the sample also has nothing to do with application code and how much RAM it can address.
As far as the number of samples that can be loaded at any one time, yes that is limited by address space -- I suppose samples can be swapped in and out of RAM to stay within the 32bit limited address space, but that would be very worky for real time audio (aka bounce and continue). But as I understand it, 32bit GUI on OS X can use a 64bit address space.
On the Microsoft side, products like Cakewalk Sonar 6 offer a 64bit version for the very reason that high quality samples with a ton of FX processing and toss in surround and you VERY quickly hit 32bit limited address space.
Some Myth's of OS X 32bit/64bit:
http://developer.apple.com/documentation/Darwin/Conceptual/64bitPorting/index.ht ml
Another good read:
http://developer.apple.com/macosx/64bit.html
Based on these specs
http://www.apple.com/logicstudio/logicpro/specs.html
It would be my guess Logic Pro 8 is again 32bit GUI code. No mention of it using 64bit address space which would be a huge "selling" point if it were and certainly listed in the specifications. "Internal audio resolution: 32-bit floating point; 64-bit precision where required..." does NOT mean it is 64bit code using a 64bit address space nor does it mean it is 32bit GUI code using 64bit address space.
Here is a good read on what 64bit computing will do for you:
http://www.cakewalk.com/Press/CakewalkWhite%20Paper_Benefits_of_Modern_CPU_Architectures_for_Digital_AudioApplications.pdf
Yes this is Cakewalk's info, but still valid and accurate -- don't read this as me trying to say one is better than the other. I'm not, I use both and when I hit the wall I bounce and proceed. The wall is just a lot further away in 64bit world -- both tools are great.
To find out if this is 32bit GUI with 64bit address space -- one would just have to load up 5GB of samples (that's A LOT of very high quality samples) and see what happens. Personally I'd think one's CPU power and FSB bandwidth to RAM would be the bottle neck.
That said, how many of you have hit the wall in Logic Pro 7.2? or Logic Pro 8? I'll be picking up Logic Pro 8 upgrade tonight regardless of it's 32bit or 64bit base.
Rob.