[Smirlouf]

Objective C, sure, but cross platform, thanks to Cocotron, an open source implementation of the Cocoa API. http://www.cocotron.org/

It's the first Cocotron-based project I see featured on HN, although it's not the first success story that they could brag about...

See also: the account of the porting of the File Magnet Uploader, then Mac-only, to Windows, using the same library. http://macdaddyworld.com/2008/10/27/adventures-in-cocotron/

[docmach]

The deployment may be cross platform, but to develop with Cocotron you need a Mac. I didn't see the reasoning behind them choosing Cocotron explained on the project page, but it seems like if they really wanted it to be cross platform they should have used GNUstep. It would also be nice to have a comparison between this and GNUstepWeb.