Single slave - multiple master MySQL replication
As of October 2013 MySQL (> 5.7.6) supports multi-source replication.

MySQL Multi-Source Replication in MySQL Reference Manual

http://www.mysqlperformanceblog.com/2013/10/02/mysql-5-7-multi-source-replication/

http://on-mysql-replication.blogspot.com/2013/09/feature-preview-mysql-multi-source-replication.html