Q: Will x86 Macs be cheaper than today's Macs?
A: A better question would be, "Will x86 Macs be cheaper than 'equivalent' PowerPC-based Macs would have been had the IBM relationship not gone south?" My answer is "no." Expect Macs to remain more expensive than PCs.
Q: Will I be able to run Mac OS X on a non-Apple PC?
A: No.
Q: Try and stop me!
A: Apple most assuredly will—try, that is. And they'll fail, just like Microsoft failed to stop people from installing Linux and MAME on the Xbox. But like MS, all Apple has to do is make sure that only Slashdot-reading, VoIP-using, PC-assembling, DMCA-breaking geeks hack their way to an "unapproved" configuration of hardware and software. If it's illegal (thanks to the Mac OS X EULA or the DMCA) or at least "technically complex and/or annoying" to run Mac OS X on non-Apple x86 hardware, Apple will be able to absorb any loss in hardware sales attributable to geeks and hardware hackers.
Q: Will future Macs use Pentium 4 CPUs like Apple's x86 developer kit announced today?
A: Probably not. I expect Apple to start with Intel's next generation of multi-core CPUs. Hannibal will have more to say about this issue.
Q: Will I be able to run Windows applications on an x86 Mac?
A: Not unless you also run Windows on it.
Q: Okay, will I be able to boot an x86 Mac into Windows?
A: No.
Q: Try and sto—
A: See earlier answer about running Mac OS X on a non-Apple PC. Update: I missed this quote from Phil Schiller. "That doesn't preclude someone from running [Windows] on a Mac. They probably will. We won't do anything to preclude that." My reaction to this new information can be found in the article discussion thread.
Q: Will I be able to run Windows on an x86 Mac?
A: With something like Virtual PC, yes. (Well, VMware, really.) Only it'll actually be fast now, close to native speed if all goes well.
Q: Will Apple provide a VMware-like environment to run Windows applications at near-native speeds on x86 Macs running Mac OS X?
A: No.
Q: Okay, then will someone other than Apple provide one?
A: Yes.
Q: Will Apple continue to design its own motherboards, or will it use commodity PC parts?
A: I think Apple will continue to produce custom designs, or will "bless" a particular PC motherboard/chipset maker (like Intel, for instance...) and contract them to build boards/chipsets that suit Apple's needs.
Q: Will Apple's planned emulation of the PowerPC ISA on an x86 chip really work?
A: It'll be "good enough," but not nearly as good as 68K emulation was on the PowerPC.
Q: Will developers get onboard with such a big change, or will they revolt and abandon ship?
A: If history is any indication, enough developers will ride out the storm to maintain the life of the platform.
Q: Will porting Mac OS X applications to x86 really be easier than porting classic Mac OS applications to Mac OS X was?
A: Yes.
Q: Will Apple maintain an internal PowerPC build of Mac OS X even after moving its entire product line to x86 processors "just in case" they ever need to switch back?
A: I hope so, if only to continue to enforce the discipline of portability.
Q: Is Microsoft worried that every Windows user is suddenly a potential Mac OS X user if Apple ever decides to give up or de-emphasize its hardware business?
A: You bet your ass they are. Don't believe the hype. Microsoft worries about everything, and this is more than a little blip on their radar.
Q: Would Apple ever do that? You know, sell Mac OS X to current Windows users to install on their existing PCs?
A: Someday, maybe, but not soon, and probably only after Apple is convinced that such a market exists and is big enough to be worth sacrificing their own hardware business. How will Apple be convinced of this? Why, by the number of people "illegally" installing Mac OS X on non-Apple hardware, of course. Multiply that number by the the inverse of the ratio of geeks to "normal" people and you get a rough estimate of the total number of potential software-only Windows-to-Mac OS X switchers. Then comes an awkward call to Michael Dell...
Q: Will x86 Macs come with a two-buttons mouse?
A: Hey, we're just taking about moving an entire platform to a new CPU architecture (again). Let's not get crazy!
Q: Did you notice that none of the pictures of PowerPC chips shown in the slides during the WWDC keynote presentation had the "G5" logo on them? Instead, they all had a generic purple badge with "PowerPC" written on it.
A: Yeah, I noticed that too. Steve angry! Steve smash IBM!
Q: Can you wrap this thing up already?
A: Sure.