This is off topic, but nonetheless; I have heard rumors that Zizek is working on a 'Hegel book', to be published sometime this summer. Is there any truth to this? 

What you need is Walter Benjamin's 'Theses on the concept of history'. All will be revealed concerning Zizek's image - which is Benjamin's just flipped. A fuller account of historical materialism can be found in Benjamin's 'Fuchs, collector and historian'

Benjamins original purpose was to use theology in the service of historical materialism - His main theoretical (and practical) mission in the Theses of history is to make a productive contradiction: i.e. the dialectic in Benjamin's thought consists of this effort to combine a messianic approach to theology (what will come) with a materialist view of history, and thereby use the 'failed' futures of past and forgotten struggles against oppression to forge a new future in the present. This is a highly original (and has been quite influential, as witnessed in f.ex. Zizek's latest work Living in the end times) way of thinking about history as such, and about materialist philosophy in particular.
And this is also why Benjamin uses perculiar sentences about revolution not being 'a fast moving train' (as Marx would have put it), but rather an 'emergency brake' to stop the chain of events and progress as such. He doesn't aim at a 'fulfillment' of history (as dialectic materialism would have it); the classless society is rather a 'disruption' of history..
The opposition in his view of history is between a circular and a linear understanding, Benjamin is here oriented towards the circular; understood as a return of the past or the coming of the.. (precisely as theology) opposed to 'progress'.
The messianic element in Benjamin's thought is both utopistic and a bold attempt of re-thinking commonly held marxist assumptions about progress and history. Marxism in this view ammounts to a kind of secularised theology - remember here what Zizek has claimed apropos Lacan; that theologicans are the greatest materialists. Yet another paradoxical approach, which is a sign of the productive origins in Benjamin's elaboration of a messianic-revolutionary perspective on history. So indeed; this is one of Zizek's greatest inspirations even today, and references to Benjamin can be found throughout his work, from The Sublime Object of Ideology and onwards.