Skype prompted an update today for v4.2 - and a pre-ticked "install chrome make chrome my default browser" option appeared.
Skype has ~521 million users - according to 6 month old techcrunch article... that's a lot of potential installs.
engine
4:30 pm on May 20, 2010 (gmt 0)
I hate those pre-selected options. I always, but always, double check the options (payload), and, always read the licence agreements for secret double whammys.