Same experiment from my gigabit link in Silicon Valley. Looks like Yahoo is about 3 times slower but far more consistent

--- google.com ping statistics ---

20 packets transmitted, 20 packets received, 0.0% packet loss

round-trip min/avg/max/stddev = 6.918/23.419/294.037/62.272 ms

--- yahoo.com ping statistics ---

20 packets transmitted, 20 packets received, 0.0% packet loss

round-trip min/avg/max/stddev = 78.056/78.940/80.940/0.811 ms

Although what's interesting is that Yahoo is really more like 10 times slower (almost every ping was in the 6-8ms range), it's just that there was just that one packet at 300ms and other at 30ms that really blew out the average.