Whats the thermal shutdown point?

212 F according to intel. Sustained temperatured higher than this can damage your logicboard.

This Intel representativeclaims:

If the processor temperature reaches 100°C or more it will send a signal to the motherboard to shut down to prevent mayor damages and most likely it won't be possible to turn the computer back in until it cools down.

That doesn't mean the Mac will shut down at 100° C though. ASC contributor OGELTHORPE has stated that will occur at 105° C. That sounds about right, but I have not been able to locate a conclusive reference.

It varies by the processor, but intel notes thermal limits for each processor on the website. As you said, though, this does not necessarily mean the CPU will shutdown:

To find the maximum operating temperature of your processor, follow the steps below:

1. Visit Intel Product Information
2. Select the Processor type
3. Select the Product name
4. Look for Package Specifications to find the Tcase value.

Thermal management for notebook processors