Revolutionary Action:"Until Now"

Greetings all:

I've just finished reading the dialogue "Revolutionary
Action: 'Until Now'," reprinted in _Language, Counter-Memory,
Practice_ and am having trouble interpreting the last
statement by Foucault. In response to an interlocutor's
statments about "the fundamental contradiction of revolutionary
action," Foucault replies:

What strikes me in your argument is that it takes the form
"until now." However, a revolutionary undertaking is directed
not only against the present but against the rule of "until
now" (p. 233). 

Would anyone mind unpacking that a bit for me? I must admit,
somewhat sheepishly, that I find it a bit cryptic -
especially in response to the passage that precedes it.
Did something get lost in translation, or I am missing
something?

thanks,
dan