Mojito doesn't try to be "write-once run-anywhere." It doesn't provide any UI or device abstraction layers by itself, beyond what YUI has always done. It's an

Mojito doesn't try to be "write-once run-anywhere." It doesn't provide any UI or device abstraction layers by itself, beyond what YUI has always done. It's an MVC app framework, oriented towards composing modules/widgets-- aka mojits. If you want to render your stuff server-side, you can. If you change your mind, it's a pretty trivial change-- and in fact you could do it at runtime (Yahoo has a search product in beta that does this after instrumenting the connection/device speeds). There will always be server-side only stuff, but at least you don't need to switch languages or frameworks when you decide what to do where. A sweet spot might be an online/offline HTML5 app that uses YQL or other webservices, for which you want to provide desktop, tablet, and smartphone versions and/or native versions via phonegap or similar. That said it's definitely not for everyone, and it's still a very young project. (disclaimer: I work at Yahoo)