MySQL 5.1 general availability is announced and it is available to be used for production use.
MySQL 5.1 brings many new enhancements in the bag for world's most popular open source database. which includes Partitioning, Row based Replication, new Plugin Infrastructure and there are many more including general enhancements.
There is a long list of new enhancements which you can go through in What's New section here.
Download it here if you are ready to put it in production or want to play with it in your development enviornment.
