If you browse around on the web or in bookstore, 'information architecture' is usually about the architecture of websites. The wikipedia definition of 'information architecture' also points in that direction.
As you may have noticed, that does not make up my work. My definition relates to the following definitions:
"Information Architecture. The shared view of information professionals on the information of their organisation (UoD) on its information as a corporate resource. The Information Architecture must be a complete view on the UoD, and therefore one will be able to derive the specifications needed to procure, develop and maintain IT-solutions." (A/I/M)
"The information architect creates an overview over the organisational information management, organizes this coherently and improves it. This is done by analysis, advise and support when developing, implementing and integrating the information management. Information management is focussed on improving the quality of product development." (Irmato)
"The information architecture, the architecture of the information flow, gives insight in the structure and relations of the information and communication management, independent of the level of automation." (From the Dutch book: Rijsenbrij, Architectuur in de digitale wereld, Zeist, 2004)
To a large extent I agree with these definitions. I'll elaborate on these definitions soon and when I find new definitions I'll post them too.