The growing number of places you need a password on just to access some content is a sure cause for increased password reuse.
Humans are simply not suited to remembering random enough password to cover all the sites on internet.
The save password option on the browser might help...
but more and more sites use the "no not save passwords" option.. forcing people back to reusing passwords.
Well, personally I just use fairly random passwords and "rememberpass" extension on firefox to force saving password even when the site does not want you to do that.. as the lesser of the evils.