The Reg gathered this nugget directly from Intel's staff, so they may have nailed this one. The extra $275 you pay for a T6700G means that your 2.33GHz T6700 CPU will have both its frontside bus and core clocks unlocked.

"Dell's website provides no guidance on what that extra $275 buys you. Its handy pop-up window that discusses processors talks about a range of Intel CPUs, and while it uses the T7600 to show how model numbers work, there's no mention about what that 'G' suffix entails."