There's good reason no announcements were made. Wall Street is far more concerned with margins than with megahertz. In order to keep Wall Street's favor Apple must maintain a high gross margin per unit sold. The past several months have seen big increases in prices for computer components. Coupled with the downward trend in PC prices, profitably selling computers at an attractive price has become both an art and a science.
Processors are most expensive when they are first released.
Further, until full production begins supply problems are a significant risk. Apple's recent decision to introduce the Sawtooth motherboard into the G4 product line, prior to the release of machines with faster processors, was a good one. When the new processors are available in reasonable quantities, rest assured that faster machines will be introduced. In the meantime, Apple is in the business of making money. It can only do so by strictly controlling inventory.