I have been searching the web and FreeScale's site just out of curiosity if there will ever be advancement beyond the current crop of G4s, I think they are 90nm 7448s at 2.0 GHz (although the last Mac Mini G4s used a 7457, I believe). I found this page on dual core processors soon to be made (January 2008) with dual 45nm cores. Hard to tell from the site if these will be G4s or not and much of their information is pretty old mentioning 2001 release dates, etc. Here's the page:
Of course I should have looked to the Information Hub of the Information Superhighway for more information:
Interesting, but it doesn't say if the new e600/e700 will be compatible with the G4 line...