Ah if software development was only that easy ... take that component from here, then that one from over there, then wire it all together in some designer tool, push a "make it so" button, release.

There are many reasons why it doesnt work like that, but I'll cut that out. It doesnt belong here.

Also, your link points to a commercial app (admittedly, it looks nice!), so how am I supposed to reuse code from that?

I am not even touching the issue of code portability, given that the iPhone lives in its own Objective-C world whereas Maemo's future lies in Qt.

You can be assured that I *did* look at code from other FOSS projects, and while doing so I changed my mind several times but we eventually decided to focus on writing our own move validation engine, simply because we want a component that integrates nicely with the rest of our program. Think of the UX, even a simple chess board needs to know a lot about chess if it ever wants to present useful feedback to the user. For example, take the dots in that app's screenshot, showing the possible moves. How does the board know where to draw them?

Nevertheless, we still dont aim at writing our own complete chess engine, that'd be insane. Again, look at our roadmap!