Apple's top-of-the-line Mac Pro hasn't been updated since the Quad-Core model received support for 16GB RAM in September of '09. The last major revision introduced the Nehalem Xeon 3500 Processor last March. Today, HardMac is reporting that the Core i7-980X and Core i7-970 processors could arrive this month.
HardMac notes that the chips are due to become available in March. If, they suggest, Apple still has a tight partnership with Intel, they could have exclusivity in the days or weeks before the official March release. Note that Apple was the first to use the Nehalem Xeon thanks to just such an arrangement.
Details of Intel's Core i7-980X Processor leaked in December. Code-named "Gulftown" the 32nm, six-core i7-980X will be labeled as the i7x ("Extreme Edition"), not the i9 as many expected. It will be the first dual-socket, six-core processor from Intel. With 6 cores and 12 threads, a dual-configured, i7-980X Mac Pro will sport 12 physical cores and 24 logical cores. Expect a top frequency of 3.33GHz.
In other words, don't replace your old Mac Pro just yet.