Isn't it the case that when someone anounces anything, in the event of
making the anouncement public, the anouncer takes credit or authority
for the anouncement and claims his/her place in the field of power
relations (like I'm doing now)?
From my understanding of Theatricum Philosophicum, AoK, DoL, etc. theannouncement is not an event in Foucault's sense, understood as belonging to the historical method of 'eventalisation', but part of the event within which are arrayed the announcer and the population to which the annoucement is broadcast. I am assuming the announcement does something; a certain kind of mobilisation, such as a declaration of war. The relation between them is defined by the dispositif that is also the rule through which the statement is actualised as the announcement. What is expressed is not the signified of the announcement, but the truth of variation (what the announcement does, ie a mobilisation) willed within the event, not only by the authority of the annoucer but also in the authority bestowed upon the announcer by the population when what is expressed (the composition of power relations) in the annoucement is annouced. The field of positivity for the capacity for truth is defined by the dispersal of statements.
Brian Massumi discusses the transmission of events (incorporeal transformations) through the mass media in Parables of the Virtual. However, I don't think this is the scale of event that Foucault was interested in when he wrote about the dispersal of statements. The concentenation of discontinuities produces a series of a different scale than that of the series of statements that define a discursive formation. The capacity to effect incorporeal transformations on the scale of the statement is another order of incorporeal transformation across discursive formations or epistemes.
D&G's critique of this conception of power relations is that they argue power is an effect of desire. Desire not in the sense of a lack, but the positive ontological sense. The machinery of desire assembles the conditions or conduits through which power runs. The announcement effects an incorporeal transformation of the given state of affairs by shifting the capacities to affect and be affected by those suspended within the power relation (announcer to act further, population to be mobilised further, etc) and machinery of desire.
For my PhD I have experimented with using a method of eventalisation in a rather esoteric domain of popular culture, which is very different to Foucault's interests. The 'popular' archive is different, the rhythm of discontinuities is much more frequent, the dispositif is weirdly distributed across the enthusiasm of the culture's participants and the cultural industries, etc.
Ciao,
Glen.