A significant source of innovation in business software is the public internet and namely web 2.0. Wikis, blogs, social networks, social bookmarking, and microblogging are examples for web 2.0 patterns which have been adopted by organisations. This trend is expected to last on, with technologies like location based services or activity streams already being discussed for business usage. However, business contexts create different requirements which are the reason for e.g. enterprise wiki systems being different from its public counterparts. This technological process of creating business software based on core functionality known from web 2.0 is hardly researched. In this work-in-progress paper I suggest a design theory for systematically passing through this process. The theory is evaluated using well documented cases of existing organisational web 2.0 adoptions. It is expected to set the ground for further research on enterprise 2.0 software as well as to provide valuable guidance for practitioners.