As predicted, at MacWorld 2006 Steve Jobs introduced a line of Intel based Apples.
In all likelihood, Microsoft and Apple have probably made an agreement not to port Windows to the Intel based Apples. (Hmm, after posting this it appears that the new Macs will run Windows Vista, but not XP, according to Apple SVP Phil Schiller.) After all, it is important for Microsoft to keep up the illusion of not being a monopoly power in the computer industry. As part of the “Who? Us? A monopoly?” non-agreement, Microsoft’s Macintosh Business Unit announced at Macworld a five-year agreement to continue to develop Microsoft Office for Mac software for both PowerPC and Intel based Macs. Apple should have asked Microsoft to sweeten the deal with some cash, considering that Microsoft's last release of Office for Mac shipped nearly two years ago, in April of 2004.
So basically Microsoft has covered its "We're not a monopoly" stance through 2011.
You can plan on seeing performance reviews of Windows Intel boxes versus Apple Intel boxes as soon as the Apple products become available.
Should the Windows boxes prove faster, count on the Windows pundits crying out “See!” and the Apple pundits replying with “So what?” If the results are reversed then reverse the cries and replies. No one’s going to shift loyalties in these two camps but the reviews and responses will provide plenty of fodder for blogs and tech articles for a few weeks.