Garett Rogers discovers that Google just changed their robots.txt file to include Disallow: /music. That suggests that Google is ready to launch a music portal, of some sort soon. Gary Price has been speculating about Google Music for over a year now.
And here are three links to the most recent evidence of a Google Music launch.
+ More Evidence of Google Music Download Service
+ Google To Host Roundtable For Top Music Industry Executives
+ Google Hiring Google Audio Employees
Postscript: Hitwise has some stats showing the percentage of people who leave Google for music sites (about 3 percent).