I have a 2 year old 2.4 GHZ Core Duo Macbook Pro which runs ZBrush OSX fine, but runs the fan pretty constantly (about 2400 rpm) after I’ve been sculpting for a while.
Has anyone compared the behavior of the fans of the latest models to the older MacBook Pros? Also any difference in behavior between Snow Leopard and Leopard?
Snow Leopard is a bit snappier. Even with 32bit-only apps. It would be wise to install it on a separate partition so you can easily revert to 10.5 for apps that are not yet 10.6 ready.
I have the next model up from yours. I use SMCFanControl and CoolBook on all my notebooks. [download both from macupdate.com] And there’s no change in fans. However I don’t have the new Nehalem book yet. 8Gigs of Ram puts it on the top of my wish list, however. 
I quit CoolBook whenever I run hardware intensive apps like Zbrush, C4D, VueInf, or Photoshop, etc… But I keep SMCfancontrol running all the time at 3000 rpm or higher. Cooler Mac = longer life, especially for the battery. Fans are cheaper to replace than motherboards.
SMC is just a fan controller while CoolBook will throttle the CPU voltage. Throttling is good when running less intensive tasks as it keeps the battery much cooler than with the fans alone.
A MacBook Pro with both fans at full speed is still waaay quieter than my tower with it’s 7 fans.
I’m familiar with the fan control software, but like you don’t want to use when running an app like Z. Other than that I don’t need the software. The computer is pretty quiet except when it does some heavy renders.
I have an 8 core Mac Pro that is very quiet. No change in fan speeds at all for ZBrush. I just like working on my laptop a lot.
Maybe it’s wishful thinking, but I’d upgrade to a newer laptop if I could get one that could stay cool enough to run Z at a high poly count with fans staying at the default speed.
I saw on Mac Rumors that there were some new entries in 10.6.2 for some new Mac Book pros.
ZBrush uses all CPU cores really well that basically means you’re running a 3D rendering while working. The fans will spin up in any machine. Just make sure you give the vents in the back clearance. And if you want a quieter machine than a MacBook Pro, you’re not going to have much luck. You might consider getting an SSD to lower the internal temperature slightly (and increase the disk speed a huge amount)
Step 1; get a Fedex standard small box
(about the same xy dimensions as a laptop)
Step 2; keep some ice packs in your freezer.
Step 3; put frozen ice packs in a ziplock bag
Step 4; put bag of ice packs into box.
Step 5; put towel on lap
Step 6; put box on towel
Step 7; put laptop on box
This works great in the hot Summer months. Although, a bit harsh on the thighs in Winter. 