Hatsune Miku, Vocaloid: world's first virtual diva [video] (English captions)

Vocaloids have been around for quite some time: http://en.wikipedia.org/wiki/Vocaloid

I find the Hatsune Miku phenomenon somewhat amusing at the moment, given the trend of overt Autotuning in pop music - while virtual singers' voices are getting more realistic, real singers' voices are being manipulated to sound impossibly accurate and digital.

It's also an interesting study in image and marketing: Crypton really pushed the concept of associating a character with the voice, as if Vocaloids were virtual pop stars whose services you could buy, rather than just another virtual instrument.