Google has authored J2ObjC, an open-source tool that can convert all the non-UI bits of Java code into Objective-C source code for use in iOS apps. It's not the first translator of this type we've ever seen, but coming from Google makes us have a serious look at this one. 

Put away your fanboy hats for a moment, and stop caring which OS has more market share or which OEM sold the most phones last quarter. Mobile will be is the next frontier of tech -- especially the Internet. Google building a robust and fully working tool to convert code for things like data access and program logic from Java to Obj-C is a big deal. This helps developers code once and port things to another platform with an automated tool, saving time and money. 

Google has stated that several of their own products are using this (no, they don't give specifics) and that it's currently between alpha and beta quality. If you're a developer, hit the source link to see all the requirements and helpful tips to get you started. If you're not a developer, just know that things like this will make mobile applications and services better for everyone.

Via Google Open Source BlogJ2ObjC project page