TheMadScientist - 7:23 pm on Jan 7, 2010 (gmt 0)

Analytics bounce rates are most useful when compared for different periods of time within the site itself - if you can get the number to trend downwards, then you are probably improving the user experience on your site. There is another kind of "bounce rate" that Google surely looks at as a metric of their own SERPs quality, and that's when a user clicks on a result and quickly bounces back to click on a different result.

I've actually thought about this quite a bit and always laugh a bit when people say their site is better because they have a low bounce rate or bounce rate should be taken into account... I have a page on one site with a +85% bounce rate which would seem bad until you know the page also has an average visit time of 4+ minutes.

The point is, personally, I think of what you are referring to as different kinds of bounce rate as two different things... Bounce rate (to me) is where someone only views one page on the site but is there long enough to make it 'count as a visit' (they probably found what they were looking for on the page they landed on: good for the visitor), where click-back rate (to me) would be your second paragraph where the visitor clicks and immediately clicks back to the results (they probably did not find what they were looking for and didn't like the site: bad for the visitor).