Thanks, dot. You should meet my supervisor. She's forever telling me the same thing ;)
Hardt and Negri put out a book after Empire called Multitude: War and Democracy in the Age of Empire, which more fully elaborates the multitude as a formulation of resistance. The concept has provoked interesting responses, especially from English speakers more accustomed to analytic thinking, often lamenting that it is not clearly defined (which is precisely the point). Some snippets of quotes:
"the multitude, the living alternative that grows within empire ... As a first approach we should distinguish the multitude at a conceptual level from other notions ... such as the people, the masses, and the working class. The people has traditionally been a unitary conception. The population, of course, is characterized by all kinds of differences, but the people reduces that diversity to the unitary and makes of the population a single identity: "the people" is one. The multitude, in contrast, is many. The multitude is composed of innumerable internal differences that can never be reduced to a unity or a single identity--different cultures, races, ethnicities, genders, and sexual orientations; different forms of labor; different ways of living; different views of the world; and different desires. ... Thus the challenge posed by the concept of multitude is for a social multiplicity to manage to communicate and act in common while remaining internally different."
To me, it sounds like the multitude is related to (and draws from) anarchy. For example, the recognition of various forms of labor (paid or unpaid, immigrants or locals, unionized or not) sounds much like the IWW modus. The notion of the multitude as a means rather than an end (i.e. it does not not need to form a monolith or legitimize its own existence; an already present starting point; a given) speaks to my understanding of anarchy.