Seems to be a lot better now. Newer versions of vBulletin have a sorta schizo way of handling it; not the most perfect way (such as how Simple Machines Forum does it) but at least it sorta remembers that you haven't yet read some threads.
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): 70/9,520.20 Ns (Equivalent to an 86% M motor.)
2015 Year-to-date: 2/735.61 Ns (Equivalent to a 15% J motor.)
The future sure isn't what it used to be...we were promised Jet Packs!