Hatsune Miku is quite fascinating. She/it also sort of puts William Gibson's "Idoru" in perspective -- the book came out in 1997: http://www.amazon.com/Idoru-William-Gibson/dp/0425158640

Relevant clip from wikipedia's summary:

"In the post Tokyo/San Francisco earthquake world of the early 21st century, Colin Laney is referred to agents of the aging mega-rock star Rez of the musical group Lo/Rez for a job using his peculiar talent of sifting through vast amounts of mundane data to find "nodal points" of particular relevance. Rez has claimed to want to marry a synthetic personality named Rei Toei, the Idoru (Japanese Idol) of the title, which is apparently impossible and therefore questioned by his loyal staff, particularly by his head of security, Keith Blackwell."

[edit: While Hatsune Miko's first release was in 2007, although she is portrayed as being 16 years old]

William Gibson - Idoru

http://www.amazon.com/Idoru-William-Gibson/dp/0425190455