This is probably the most ridiculous rumor yet. I have very little faith in AppleInsider's "extremely reliable sources and a several-month-long investigation." This one just doesn't make sense, and belongs on Page 2 at best.
The PowerBook, while having been updated only a few weeks ago, is designed to be an on-the-go workstation for professionals...professionals that use big programs like Photoshop, which isn't a universal binary yet. Yes, Rosetta is great, and will help smooth out the transition, but it isn't a replacement for a native third-party application, especially if running this application is vital to your daily work!
The iMac, which has also been updated recently, is another very unlikely candidate for Intel processors. The PowerPC G5 likely outperforms anything that Intel has to offer at this time.
Let's remember here folks that the transition is slated to take place from 2006-2007, and not all programs are universal binaries yet.
The Mac mini, on the other hand, would be a wonderful recipient of Intel processors. Aside from a few speed bumps, it hasn't really been heavily updated at all since it's introduction, and from what I've heard sales have been slowing since the "specification grab bag" incident. The Mac mini, after all, is pretty much an experiment if you think about it, why not throw an Intel chip in it? If they do so, it should come with a Core Image capable graphics chip and Front Row. Releasing an Intel Mac mini as early as January could also pressure developers to expedite their universal binary efforts without alienating them.
Apple is in a transition phase right now. Transitions are difficult and need to be carefully planned and orchestrated in order to be successful. Apple has proved to be quite capable of making bold and exciting changes, and the switch to Intel processors will be no exception. They will do it correctly, and not rush into things, or make poor decisions. After all, this is Apple we're talking about!