What is the most efficient way to deliver the same set of functions on different mobile platforms (Windows, Blackberry & Android, possibly iPhone)?
What are your real life experience of the conversion of a common design to the minimum possible sets of source code? What are the good/bad tools?
If you are targeting native applications then use a cross compiler tool. There are several of them in the market
However, none of these tools are mature enough to target all the possible platforms. ( I am sure none of them will support Windows Mobile 7 right away ).
If you are targeting Mobile Web platform then use a combination of device detection library ( WURFL, Device Atlas ) and a device rendering library ( WALL ) to generate content customized for each platform.