Vocaloid is a singing voice synthesizer, a program in which anyone can create a song (great if you can't carry a tune with your own throat). This sort of thing has been growing since 2004 in Japan. The last bit of knowledge I have on this subject is that Lady Gaga will be using Miku (a vocaloid character) to open her next concert.
There you go, the entirety of my expert knowledge on the subject. Now, if only I spoke Japanese, I could sing along.