What work has been done on cross-platform mobile development? [closed]

The HTML5 standard has support for releasing stand-alone HTML5 apps. Essentially a HTML5 app is a bundle of HTML5, JavaScript and CSS files that will run stand-alone in the browser of the desktop or device. You can distribute them like any other program, including selling them on the iStore for the iPhone.

The support for this is patchy at the moment but is likely to improve tremendously in the next year or two.

Google for HTML5 apps for information and resources. A good introduction to HTML5 is the online book "Dive Into HTML5" by Mark Pilgrim. This is a work in progress, but sufficiently complete to be useful.

There are 2 [newish] solutions to exactly this issue:

rhomobile

and

phonegap

I think there best chance for cross-platform mobile success is the Web. Just write a very simple Web application for what you want to achieve. It should work on the Nokia S60browser, Iphone and Android.

That's already a lot of mobile devices...

Appcelerator, PhoneGap (acquired by Adobe, plus it's now standardized as Apache Cordova), Intel XDK (formerly called appMobi) and Rhodes (acquired by Motorola Solutions) are all open source and create hybrid apps (natively packed with html ui, with the possibility to add some of your native controls).

If it's a game, your only professional choice for a free engine that can be used for commercial development is Unity3D. For 2D games, cocos2d-x is also available. Additionally, Vuforia can be used for AR and LiquidFun for physics.