Do you know how easy it is to port touch-friendly UI frameworks/SDK's such as MOAI (
http://getmoai.com/) to Ubuntu? Damn easy.
In fact, its already done: and right now, MOAI - and similar tools, just like it (Love2D, Cocos2D, &etc.) - are already out there, running on the existing OS's, and providing multi-touch interfaces that definitely compete with existing Frameworks/SDK's. There is little that Cocoa does, for the 2D gamer/mobile developer, that MOAI cannot do, also. (Granted: native interfaces are a weakness, but then again: non-native, truly cross-platform UI's are a STRENGTH in the face of the existing market)
By making this move, Canonical has just invalidated all the proprietary bullshit the average Objective-C developer has to contend with, in order to develop an app for the mobile platform. Same with Android - both Objective-C and Android investments have just been bumped down a few tens of points, in my opinion. Why bother learning proprietary locked-in crap, when you can pick a framework that will run easily on all of the platforms, including the up and coming new Ubuntu-Mobile?
Where once we have over-specialization and a slavish devotion to technocratic dogma from an oppressive regime (Apple, and in lesser yet still significant ways, Android too), we now have a real ability to choose our tools and standardize on the ones with which we most feel comfortable.
Make no mistake, this is a genius move. Not only do we have Mobile becoming Desktop becoming the Cloud, finally, but we have it with Open Tools, that no other company has the balls to produce.