WSO2 has announced the release of WSO2 Mashup Server 1.5.2. This release introduced the support for Data Services (Exposing Database, Excel sheet, CSV as a service), Open ID Logins and personalized dashboards to manage mashups and some security improvements. Just have a look at the release note for all the details about the new features, fixes of the release.
If you are new to Mashup Server or to develop Mashups, just have a look at the series of screenshots released by WSO2 sometime ago. That will no doubt take you from zero knowledge to a comfortable state to write full-fledged mashups.