"Nope. Apple doesn't have a monopoly in the phone market"

It's a common misconception that you have to have a monopoly to run afoul of antitrust law. You don't. It also goes the other way--having a monopoly is not necessarily a violation of antitrust.

For instance, mergers have been shot down on antitrust grounds even when the merged companies would have had under 50% of the market.

Antitrust is more about the effects of actions on competition, rather than market share, although there tends to be a correlation between the two.

Yes, but is relevant if they are not judged to have a anti-compoetitive effect on the market as a whole. Clearly a company does not have to be a 100% monopoly in the literal sense to run afoul of anti-monopoly laws, but these sanctions are not applied to EVERY company. In Europe, it is not even a matter of behavior illegal for 'monopolies' to engage in, if they are a 'monopoly' there can be sanctions.

Thank you, good sir, for posting this reasoned, thoughtful, and accurate post.

People disagree?

Yeah, but the timing of the news could possibly end them in court.

Had they done this months ago, they'd likely have not had a problem. But 4 days before CS5's release? I could see that adobe has already filed suit.

could apple then sue them back because they're talking about something that is still under nda?

Perhaps sue John Gruber, who put it out there on the web.

Once out there, Adobe was likely under no obligation to not talk about it.

How is "market" defined, legally? They certainly have a monopoly over the "iPhone" or "iPhone App Store apps" markets. Of course, that reasoning could get absurd pretty quickly, so I'm sure it must be defined at a pretty generic, high level.

It's a gray area. One of the issues in the Microsoft antitrust suits was: what is the "market" in which Windows operates? Obviously, operating-system software of some sort, but which platforms count in the total? Microsoft was arguing that they make basically "an OS for computers", and so their market share should be computed after including Unix workstations, Mac desktops, maybe even Unix servers and IBM mainframes in the totals. Netscape were arguing that the relevant market was the OS market for IBM-compatible home-and-office PCs, in which Microsoft had a much higher dominance.

It's a good question and it turns out to be the most important issues for any anti-trust action. If you are really interested, I would encourage you to look up some famous cases and read the decisions in some of the cases.