Bethesda’s latest game uses an updated version of the Gamebryo engine (Oblivion). This benchmark takes place immediately outside Vault 101. The character walks away from the vault through the Springvale ruins. The benchmark is measured manually using FRAPS.

Gaming performance clearly goes to the Athlon II X2 and the Phenom II X2. Because of its high clock speed and very high core-to-cache ratio, the Phenom II X2 550 is actually faster than the Phenom II X4 940 in this test. Note that Fallout 3 isn't particularly heavily threaded so the X4's additional cores don't do much good here.

AMD continues to hold on to the gaming performance lead.
FarCry 2 ships with the most impressive benchmark tool we’ve ever seen in a PC game. Part of this is due to the fact that Ubisoft actually tapped a number of hardware sites (AnandTech included) from around the world to aid in the planning for the benchmark.
For our purposes we ran the CPU benchmark included in the latest patch:

In the newer game engines we see the E6300 catching up to the Athlon II X2 250. The old Pentium 4 660 starves our testbed's GeForce GTX 280 for data; it's horrendously slow.

In the article you seem to imply a tremendous difference in that 2meg to 3meg jump but your single data point doesn't show that conclusion.
In your example there is a ~9% increase in performance when going from 2 to 3 megs, but there is also a 4.5% increase in clockspeed between the 2 chips. So at best (in this example) you have a 5% difference, which while significant, I would't say it was tremendous.
Can you comment on whether you did any further tests with identical frequencies?