Go here:
http://www.mosr.com
Most everything I have seen them post has come true. Also they update and kill rumors when they find errors and such. Check the archives if these aren't on the front page when you get there, or for verification of past rumors...
"Friday, March 16
Dual-processor 667/733MHz PowerMacs due by April
[Rumor]
According to reliable Apple sources, new PowerMac G4 configurations including dual-processor versions of the 667 and 733MHz models will become available in a matter of weeks -- possibly before the end of the month, but almost certainly by mid-April. Quad-processor versions have been considered, but due to the high cost of PowerPC 7450 processors at present, Apple does not expect to introduce four-way MP until its next major PowerMac revision this summer."
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Also:
"Wednesday, March 14
Gigahertz PPC 7450 G4s targeted for August
[Rumor]
New information acquired through Motorola sources points to firm plans for the company's new PowerPC 7450 processor, now used in Apple's PowerMac G4 667/733 models, to scale in two steps to 1GHz.
Apple, however, is presently expected to announce both steps in a single event: Macworld New York this July. Similarly to the company's unveiling of its first two 7450-based PowerMacs, some of the announced models will be available immediately (733 and 800MHz versions), others "soon" (866 and 933MHz), and the high-end model at 1GHz will probably not ship until the end of August -- about six weeks after Macworld.
Other big news coming out of Motorola includes plans to co-develop the PowerPC 75xx processor family, also known as the G5, with IBM. To address concerns that Motorola may not be able to keep up with the needs of the Mac platform going forward into the 2002 timeframe and beyond, both companies will actively develop their own versions of the G5. Expect to hear more very soon..."