The Spider storage engine should be already known to the community. Its version 2.5 has recently been released, with new features, the most important of which is that you can execute remote SQL statements in the backend servers. The method is quite simple. Together with Spider, you also get an UDF that executes SQL code in a remote server. You send a query with parameters saying how to connect to the server, and check the result (1 for success, 0 for failure). If the SQL involves a SELECT, the result can be sent to a temporary table. Simple and effective.
In addition to the Spider engine, Kentoku SHIBA has also created the vertical partitioning engine. Instead of splitting tables by record, you split them by columns. You can define a table with column A and column B, with primary key K, and another table with column C and column D, with primary key K. The vertical partition engine allows you to define a table with columns K, A, B, C, D, which looks to the user like a regular column. The backend tables can be of any engine.
There is a MySQL University session about the Spider and VP engines on November 26th at 15:00 CEST. Free attendance!
The slides are online: Sharding for the masses