Daniel Torres-Salinas, Alberto Martín-Martín, Enrique Fuente-Gutiérrez have self-archived "An Introduction to the Coverage of the Data Citation Index (Thomson-Reuters): Disciplines, Document Types and Repositories" in arXiv.org.
Here's an excerpt:
In the past years, the movement of data sharing has been enjoying great popularity. Within this context, Thomson Reuters launched at the end of 2012 a new product inside the Web of Knowledge family: the Data Citation Index. The aim of this tool is to enable discovery and access, from a single place, to data from a variety of data repositories from different subject areas and from around the world. In this short note we present some preliminary results from the analysis of the Data Citation Index. Specifically, we address the following issues: discipline coverage, data types present in the database, and repositories that were included at the time of the study.