Apple and Intel
Yes it's the big news in the tech world. Apple is switching to Intel CPUs. It's a pretty shocking turn of events. It is very difficult to say if it is a good move or not. Here's what I think are the pros/cons:

Pros

• No more IBM. Clearly this is as much about the falling out between IBM and Apple as it is about Apple suddenly becoming enamored with Intel. As Steve Jobs pointed out, IBM has not delivered on the clock speed for the G5 and has not delivered a G5 suitable for laptops. It's really no wonder for IBM. If you look at the direction they've headed, creating desktop/laptop processors just isn't part of their plans.
• Intel is dedicated to desktop/laptop processors. Intel is once again battling hard against AMD for dominance on the desktop. Right now most people would agree that they are behind on the desktop, in terms of technology. However, they are clearly dedicated to furthering desktop CPU performance. They are also clearly ahead of AMD when it comes to laptops. Again, they appear to be dedicated to maintaining this lead. Intel's roadmaps for their desktop and laptop processors looks promising, especially now that they've finally letting the megahertz megamarketing machine dictate their designs.
  
• Better compiler support. One thing people often overlook is how much effort Intel puts into their compilers. Their compilers do a very good job of optimizing for their platform. I don't know if Apple was really relying on GCC, but it was terrible at optimizing for the G5 (and the G4 for that matter.) This should really allow for better use of the underlying CPU by most programs (though there are some potential exceptions, see below.)
• Lower prices? Apple got some good prices from IBM, by most accounts. So it's hard to say if they will get significantly lower prices from Intel or not. Still, Intel is always competing with AMD, and one would guess that switching from Intel to AMD would be very easy for Apple. So that would always be a card that Apple could play to drive a good bargain from Intel on the CPUs and chipsets. It's also widely known that Intel chips in for Dell marketing, and a similar subsidy would seem reasonable for Apple.

Cons

• Rearchitecturing has historically cost Apple about half of its market share. It's very likely that they will sell a lot less Macs until the x86 versions are rolled out. So if you're a Mac user and need to buy a new computer this year or next year, but don't want to buy a PowerPC based Mac because its going to become really obsolete very soon, then what do you do? Buy a Dell of course. There goes the market share.
• Developers are going to be upset. Jobs basically said that all developers using Code Warrior are screwed. That's most longtime Mac developers right there. Nobody likes being forced to switch to XCode. Developers aren't going to like the alternative either: sticking with Code Warrior and its PowerPC binaries and going through the Rosetta emulator (no matter how great Jobs says this thing is.) Apple saw this when they rolled out OSX. It took forever for Quark to be ported to OSX, and the Adobe products suddenly became much more at-home on Windows than on a Mac for the first time. All of this can cause people to switch to another platform, and even worse can cause Mac people to doggedly stay with the old platform that ran their apps better.
• The x86 architecture. It definitely has its problems and limitations. People (including Steve Jobs) have been predicting its demise for a long time. It has stuck around because of backwards compatibility. If you remove that benefit, it's hard to understand why anyone would choose it.
• Battling Hackers. Hackers everywhere are now dreaming of running OSX on the whitebox system they put together from parts bought on eBay and Newegg. Apple has already had to answer the question "Will OSX run on non-Apple hardware?" with a resounding "No!" Their rationale is obvious: they charge a premium for their hardware. So they will probably resort to a BIOS trick or maybe even using some kind of DRM built into the Intel processors they choose. I'm sure they will be very clever about it, but this is a losing fight. Just ask record companies, movie companies, or for that matter, Microsft and Adobe. Actually Apple should already know this. It is easy to defeat the DRM on songs sold from iTunes, just use the open source JHymn. This can easily become a time-consuming effort, putting up a new protection scheme only for hackers to defeat it a few hours later. Actually, maybe they did learn from iTunes and JHymn. Maybe they will put some protection scheme, but won't bother trying to constantly beat the latest hacks.