Despite many years of ubiquitous computing (ubicomp) middleware research, deployment of such systems has not been widespread. We suggest this is in part because we lack a shared model for ubicomp environments, and that most existing systems are constrained to single administrative (and network) domains. To address this, this paper presents work in progress toward a core common ubicomp environment model derived from an analysis of several existing ubicomp systems. This model lends itself to interoperability across domains, and for use in a middleware platform used to adapt existing ubicomp systems to this common model for wide area access. This platform design, based on enterprise application integration (EAI) approaches, highlights the benefits of Web Services and Semantic Web technologies for exposing ubicomp environments to applications outside the administrative domain.