Adoption has been limited to the supporters of the specification. To make matters worse, IBM, Oracle (BEA) ended up building their own proprietary SCA implementations (runtimes and extensions to the SCA programming model) to run their own SOA-related product offerings. So, if you build on top of these proprietary implementations, vendor lock-in is a given and you compromise portability of your composites/services.
Contrary to the above, there are some open implementations like Fabric3 and Apache Tuscany. Portability remains a question even with these open implementations because of non-standard extensions to the OASIS SCA specifications.
Google searches on SCA return results that are dated (pre-2009).
Apache Tuscany provides runtimes for Java and C++ (also referred to as Native).
Fabric3, stewarded by MetaForm Systems, is a complete platform for building service-oriented, event-driven applications.
Eclipse SCA Tools project is undergoing incubation under the umbrella of SOA Platform Projects. Going by the SCA Tools Wiki and the code-commits at the GitHub mirror, this project does not seem to be active in the past year.