Bruce Schneier, in a Wired story, 'Everyone Wants to 'Own' Your PC', classifies DRM along with worms and viruses as all being specifically intended to remove control of a computer from the user/owner. This is a particularly succinct quote:
"When technology serves its owners, it is liberating. When it is designed to serve others, over the owner's objection, it is oppressive."
I think that pretty much sums up what 'architectures of control' are: products, technology and environments designed to serve someone other than the user.
Now that 'someone else' might be 'the good of society', but in more cases than not, the someone else is a company wanting to enforce a business model on the user, or a government wishing to enforce an ideology or mode of behaviour.
(original story via Boing Boing)