Snow Leopard didn't "raise the bar" for Intel Macs above what Leopard already required. It did however end the ability to run the latest OS X on pre-Intel Macs. I would expect ML to run on the collection of old Intel minis (with RAM upgraded to 2 GB) I have running Lion right now.
@OP The seed note states 10.8 is for 64-bit machines only (currently). Given the fact that the MacBook is dead, I don't believe Apple will support it. But who knows.
As long as the Mac is using a Core 2 Duo processor, then it will work. While the Core Duo was 32-bit (can only go up to Snow Leopard), the Core 2 Duo is 64-bit, the requirement for Lion. Also, I think they have to keep supporting the Core 2 Duo for a while since tons of machines made by Apple used the Core 2 Duo up until about a year ago until everything switched over to the Core-i series.
EDIT: Seems like its reported that machines with Intel GMA 950, Intel X3100, or ATI X1600 graphics will not be able to run Mountain Lion. So that may stop the upgradability of any MacBook that was made earlier than late 2008 when it was updated to the NVIDIA 9400M. Original thread here: https://forums.macrumors.com/threads/1325071/