I use PyObjC, and it's makes Cocoa development quicker and less painful, but it isn't a replacement for knowing Objective-C. Especially when you get into the Co

I use PyObjC, and it's makes Cocoa development quicker and less painful, but it isn't a replacement for knowing Objective-C. Especially when you get into the CoreGraphics stuff and occasionally crash through the floor into OpenGL, Python isn't going to save you (much to my regret). Despite the negative hype against HTML/JS, it isn't hard to create cross-browser code using that combination. I wrote a project called sparklines.js a while back, which uses the canvas element and it renders appropriately on all major browsers (including IE using http://excanvas.sourceforge.net/ http://excanvas.sourceforge.net/). The speed of javascript is going to be sufficient as well for anything except the most extreme projects (I also wrote ptdef.com, which is a tower defense game in html/javascript. It plays poorly on I.E. but fine in more modern browsers, and its far more complex (pathfinding, etc) than the JavaScript you'll probably be dealing with). Beyond that, using an html/javascript combination you can create content that renders correctly on the iPhone, in desktop applications (well, at least on OSX you can use the WebView to render arbitrary html/css/javascript), and on the web. It's also an open stack, which is my largest complaint against AIR. In the end, though, I think the hard part should be developing the underlying algorithm to display the visualizations you are interested in, and transplanting it to another platform later shouldn't be impossible. Where you start out really depends on what you want to build. ;)