Receptional_Andy - 1:32 pm on Sep 5, 2007 (gmt 0)

The average man or woman on the street doesn't know this, doesn't care and will not even think of passing the cursor over random images to see if they are linked.

These aren't random images or clicks though - it's learned behaviour. If a logo in the top left hand corner links to the logo on all of the 'big' websites that users visit when they are starting to use the internet (think Google, Yahoo, Hotmail, Amazon etc.), then visitors learn that this is the behaviour to expect, and this is reinforced when they find that the new sites they use do this also. I would expect more usability problems with a logo in the top left that didn't link to the homepage.