Collaborative infrastructures are emerging as one of the key elements to enable collaborative applications for human-centric collaboration. These infrastructures have to provide the system components needed by the collaborative applications and, at the same time, comply with service orientation architectures principles. This paper discuss the main results of the consultation process carried out since beginning 2006 in order to identify the 12 research challenges on this area and the three building Blocks needed for Collaborative Work Environments (CWEs). A high level middleware, called upperware, and a reference model for CWE have risen as two of the most desirable research outputs for medium-long-term. If the Building Blocks defined through the consultation process are realized, collaboration platforms will meet the needs of workgroups across enterprises? borders.