From the Disconnect FAQ:

On Firefox, if Disconnect is the first blocking extension you install, then Disconnect will work even if you subsequently install other blocking extensions. On Chrome, Safari, and Opera, it's the opposite: in order for Disconnect to work on these browsers, it must be the most recent blocking extension installed.

Do you know what effect this has on extensions like Adblock Plus and NoScript? If I install Disconnect first, are those addons going to do less for me?

This is the first I've heard about installation order affecting how well the addons work. I'd like to make sure I've got the right info before informing others.