I wouldn't say Intel started multiple threading, hyperthreading simulates the enviroment of multicore processors but is nowhere close to the real thing. Both companies knew that multicore CPUs were inveitable as both have hit a bit of wall as increasing clock speeds results in more heat than the silicon can handle safely.
Although I will say that AMD has actually still taken strives to improve their single core heat dissipation, with voltage constantly dropping on these cores and the same said with power consumption, as well as plans to decrease the size and pin count of chips, single cores may not be as dead as people may have thought.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w