Listing the licenses used on an installed system?

[Sebastien Bacher]

Hey,

I'm looking at the "about this phone" panel [1] for the touch image, one 
of the feature included is a "Software licenses" screen which:
"should navigate to a single “Software Licenses” screen that consists of 
a single text view listing all the licenses for included software (since 
there is no other way to access that information). "

Does anyone know if we already have tools doing that, or what would be 
the best way to get those informations? From a quick discussions on IRC 
yesterday the idea that came out was basically to read/dump 
/usr/share/doc/*/copyright ... does that seems a reasonable approach? 
Checking on an android device, their equivalent panel is slow and 
dumping tons of informations as well...

Cheers,
Sebastien Bacher

[1] https://wiki.ubuntu.com/AboutThisDevice#Phone