CainIV - 12:09 am on Mar 1, 2011 (gmt 0)
For several years, Matt Cutts, along with other Google spokespeople, have been talking about the fact that "bounce" is a noisy signal. Yea, they measure it but apparently they can't use it for any heavy lifting in the algo.
This only makes sense. In many industries what defines a bounce is purely subjective, and often a bounce means success, in the case of a telephone call or sale delivered via a different domain