It's not quite auto-mark but if you use the "Forum Tools" drop down menu, there is a selection titled "Mark Forum Read" that does exactly what it says.
There is also a "Quick Links" feature that marks all forums read.
Not automatic by any means but the functions are there.
Kit (AKA Cranky Kong)
Total Flights/Impulse as BAR (2010): 69/9,155.86 Ns (Equivalent to a 79% M motor.)
The future sure isn't what it used to be...we were promised Jet Packs!