Advances in wireless communication and mobile computing extend collaboration scenarios. Mobile workers using computing devices are currently able to collaborate in order to carry out productive, educational or social activities. Typically, collaborative applications intended to support mobile workers involve some type of centralized data or services, because they are designed to work on infrastructure supported wireless networks. This centralization constrains the collaboration capabilities in ad-hoc communication cases. This paper introduces the concept of Service-Oriented Mobile Unit (SOMU) in order to reduce such limitation. SOMU is an autonomous software infrastructure running on a computing device; it is able to be integrated to ad-hoc networks and it can interoperate with other mobile units in ad-hoc collaboration scenarios. In addition, the paper presents the challenges faced when designing and implementing the SOMU platform. It also describes an application developed on SOMU.