The attack is based on the built-in procedure that Pentium based chips use when they overheat:

When the processor begins to overheat or encounters other conditions that could threaten the motherboard, the computer interrupts its normal operation, momentarily freezes and stores its activity, said Loïc Duflot, a computer security specialist for the French government's Secretary General for National Defense information technology laboratory.

Cyberattackers can take over a computer by appropriating that safeguard to make the machine interrupt operations and enter System Management Mode, Duflot said. Attackers then enter the System Management RAM and replace the default emergency-response software with custom software that, when run, will give them full administrative privileges.

Every computer that runs on x86 chip architecture may be vulnerable to this attack, including the millions of computers that the U.S. government and industry use, said Dragos Ruiu, the conference organizer. He is a Canadian computer security consultant for businesses, governments and the U.S. military.

Well, if root can replace System Management Mode there are some interesting possibilities for evil. SMM runs at permission levels beyond ring0, think of it as ring-1. From there you can escape any virtualization, any chroot jail, probably even escape from inside an emulator like VMWare if you can manage to execute the exploit without the emulation catching it and simulating it.