gyppo - 8:18 am on Mar 26, 2012 (gmt 0)
Pretty sure I've read a quote from MC stating they don't use these sorts of metrics in the algos.
I mean, on one of my sites if the user bounces it means they've found what they're looking for. If they go back to the SERPS it might indicate that they haven't, but you have to remember that everyone's browsing habits are different - i.e. some users might open up all tabs on the page then browse one by one until they find what they want etc.