As if the changes happening for MySQL 4.1 weren't enough, the developers are already hard at work planning and prototyping features for including in MySQL 5.0. This list of included features will grow dramatically as developers actually get closer to an alpha release, but in general you can look forward to the following in MySQL 5.0:
Stored procedures, based on SQL-99. The developers are also endeavoring to use external languages and implement compatibility with languages such as PL/SQL and T-SQL.
New functionality, such as elementary cursor support.
Additional strides toward standards compliance.
Ongoing speed enhancements.
Continued internationalization and usability enhancements.
As subqueries are to MySQL 4.1, stored procedures are The Big Thing for MySQL 5.0.