Georg, Andrey and Ulf have been hard at work designing, implementing and testing a replacement for libmysql only for us PHP users. The idea is that mysqlnd can leverage all the internal PHP infrastructure for communication and memory management. It can also be much more PHP aware, removing old cruft we do not need while adding extra goodies just for us!
This means the PHP memory limit will finally be honored, PHP user streams will be able to hook into the communication with MySQL. A client side query cache promises speed improvements and the fact that data does not need to be moved from libmysql to PHP should also stream line things. They are also looking to improve support for persistent connections.
While originally developed for PHP6, mysqlnd now also runs on PHP5 and talks to ext/mysqli and ext/mysql with PDO support planned. More over the source is available under the PHP license and the code will hopefully one day make it into the main PHP CVS.
Now the mysqlnd is looking for the first brave testers. Willing to hammer the code with benchmarks and more importantly real world PHP application code. Particular need is for high load stress testing. Please pass all your feedback on to Georg and his team my mailing firstname.lastname@example.org (see http://lists.mysql.com/ for how to subscribe).