Nominalisations, like agentless passive constructions, are a linguistic structure to have received much attention in CDA, especially Critical Linguistics and the sociosemiotic approach.  Nominalisations are processes transformed into nouns.   They are 'reduced' representations which offer ideological opportunities (Fairclough 1989: 103; Fowler 1991: 80).  Specifically, certain informaton, e.g. participants, time, and modality, may be glossed over or 'mystified' in nominal forms. Nominalisation thus permits 'habits of concealment, particularly in the areas of power-relations and writiers' attitudes' (Fowler 1991: 80) 

The significance of nominalisation, however, has recently been the subject of debate in an issue of Discourse & Society.