As if I did not have enough modules to take care already, I just started a new one. It is still on its beta version as I did not have much time to test it, and write a decent API. It is available in the usual place: https://metacpan.org/release/AMBS/Lingua-Identify-CLD-0.01_01
This is an interface to a library by Google for language detection. As far as I could understand, it is part of the Chrome browser, and was just released as open source. Details here: http://code.google.com/p/chromium-compact-language-detector/
It is available at GitHub, and I am happy to receive issues or pull requests. Just bear in mind that no API is still defined (although I have an idea of what I want) and that I do not have much time to solve your issues right ahead.
Finally, a thanks to Jean Véronis that pointed me the library and asked kindly for a Perl interface to it.