I wrote before of the rumoured Antares 970MP dual-core next generation G5. Think Secret revisits the topic, this time focusing on the single-core 970GX version of the chip. Rumoured specs for the chip are a clockspeed of 3 GHz, and 1 MB L2 cache, double that of the current 970FX. In essence, this is the single-core version of the 970MP (which makes one wonder if this could represent the dual-core 970MP chip with a failure of one of the two cores). This doubling of the L2 cache and the increased clockspeed in a single-core chip represents a logical evolution of the 970 design, and would make for a nice upgrade for Apple's machines.
IBM has also released a PDF which mentions the eServer JS20++ (page 18), which has not yet been released. If by their nomenclature, the JS20 represents the version with the 1.6 GHz 970, and the JS20+ represents the version with the 2.2 GHz 970FX, it would not be a leap to think that the JS20++ would use the new 970GX chip. As a side note, this document also confirms that IBM utilizes the U3 Northbridge designed by Apple.
In addition, Think Secret mentions 1.6-1.8 GHz low power chips for PowerBooks, although it's not clear if these would be versions of the 970GX, tweaked 970FX chips, or something else. The mentioned clock speeds seem reasonable, especially considering IBM's previous hints of a low power 1.9 GHz G5 with a max power utilization of 30 Watts, for laptops. Plus, 1.6-1.8 GHz G5s would make for the perfect update to the current G4 line, which uses 1.33-1.5 GHz G4s.
Finally, while IBM's latest 90 nm chip yields have not been stellar, they have been quickly improving, and IBM claims they should get a 40% improvement in chip output this quarter. (It is not clear if that improvement is purely due to increased yields or includes additional wafers.) However, Apple states that 2.5 GHz 970FX Power Macs will continue to be in limited supply this quarter, so it may be quite some time before we see the PowerBook G5 or Power Mac 970GX (or 970MP). Macworld 2005 is in January, but it may be as long as WWDC in June before we see any such generational updates.