You caught that too, eh? Its pretty impressive, but not very practical. A 4Ghz Core 2 Duo matches that thing. =/ Still, goes to show that Intel wasn't all hot hair when it said that the Netburst architecture would hit between 5 to 10Ghz. If they hadn't run into thermal leakage, that architecture would've gone places.
It's at 8Ghz, not 5. And the architecture has always been capable of this speed. Remember that Intel initially wanted this architecture to hit somewhere between 5-10Ghz in terms of retail processors. This was never possible because the processors started to leak too much heat after a certain point. But in conditions like those (they're using LN2, not water cooling), the heat element is entirely taken away. That means that you can pump as much voltage into it as you want, and it'll take the processor to it's physical limits.