I have to say that I do not agree.

As Jean Louis Gassee points out in “The Adobe – Apple Flame War” permitting cross-platform development would imply that Apple would accept a level playing field defined by the capabilities of some 3rd party cross platform development tool. If that tool does not support a specific feature it won’t be in the application. It is very unlikely that “that tool” will support platform specifics unless they are widely available as this is against the very nature of a portable toolkit.

In reality we are of course talking about Flash. Flash is – IMHO – the antithesis of an innovative platform. It has been a pain in the neck on some many aspects (usability, stability, resource usage to name a few) for a so long time that I would see a widespread adoption of Flash as a mobile development platform as stifling innovation.

A simple example: Assume for a second that “pinch zoom” is an Apple-only UI feature (it is to some extend).
As it’s not portable there won’t be “pinch zoom” in a portable toolkit thus no pinch zoom in portable applications. Who looses? The users. If it’s not on all platforms you don’t get it. Most – especially corporate – developers may not care that much as they will deliver the same suboptimal user experience on all platforms. Some will go the extra mile and develop native applications as they differentiate against other Apps based on UI experience. Apple, as a hardware vendor looses as they lost differentiating UI features in some applications. Apple is simply “protecting their investment” which is their right to do.
Although I have an opinion about Apple’s handling of the App Store and the iPhone ecosystem in general, I won’t join the flame wars here.

It is simply my opinion that – as Martin wrote “we are only in the beginning of the new mobile age” we need room to innovate and we need competition which is exactly what a portable application landscape won’t give us. “Mobile cross platform died” – so what.

I assume that – once the mobile application space has matured and evolved  and we are looking at more stable platforms I will reconsider my opinion but for now I think Apple’s move – which I also instinctively  dismissed as being ‘evil’ –  will eventually help the whole market.

Unless of course you are assuming that the mobile application market has already been won over by Apple once and for all – an opinion which I haven’t heard so far.