Steve Jobs just said (I guess I should say, Real Steve Jobs, hehe) on his blog:

…We want native third party applications on the iPhone, and we plan to have an SDK in developers’ hands in February.

…Nokia, for example, is not allowing any applications to be loaded onto some of their newest phones unless they have a digital signature that can be traced back to a known developer. …we believe it is a step in the right direction.

This seems to indicate that the application installer – which will in all probability be iTunes – will check if the application is properly signed. Whether they’ll allow developer-signed apps is anybody’s guess, but I wouldn’t rely on it. (Signed apps is one of the 300 Leopard features, by the way. I’ll comment on the Leopard day announcement in a few days.)

I wrote two weeks ago:
Rainer Brockerhoff wrote:

Conclusions:

– the current generation of iPhone/iPod touch will remain closed forever, just like the first generations of iPods; (I was wrong there, and a good thing too!)

– an SDK is likely to come out only after everything (especially the hardware) has stabilized;

So the February OS X version will be the first one with stable, public APIs… meaning current apps, written to reverse-engineered specs, will probably have to be seriously rewritten.

Rainer Brockerhoff wrote:

– Apple is unlikely to invest efforts into implementing TrustZone in the current generation, unless Moorestown (or whatever else they might adopt in the future) has a similar security feature – and maybe not even then

Now I wonder how they’ll handle such a hypothetical future hardware migration… probably fat binaries, with the “other” executables being stripped out by iTunes when installing an app; this would be the most flexible without upping memory footprint on the phone side.

Update: Seems that Intel and ARM are collaborating on new TrustZone implementations… might that foreshadow TrustZone on Moorestown…?

Now, some people say this proves that Apple is listening to complaints and that they’re changing their original plans; on the contrary, I think this had been the plan all the time, but the Leopard delay also delayed the SDK. Regarding the timing of this announcement, this might be a trial balloon to see if they can minimize the inevitable profit-taking after next week’s earnings announcement. Hopefully that will happen.