Open source Skype client under development

I see your point. I was thinking that there were pieces of software in contrib that were capable of using non-free libraries to perform certain functions[0], but perhaps they're only allowed into contrib if they add functionality by calling an inarguably standalone executable that you may choose to install from elsewhere.

This has however led me to conclude that there is a good argument for a fair bit of software compiled for Windows being technically not distributable, depending on how generously the 'system libraries' exception is interpreted.

[0] Like hugin, say - although that's a patent issue rather than a copyright one, and I think that's actually in main because it doesn't *need* the problematic part. Okay so that was a bad example :P.