MySQL.com has an announcement (posted a little while back) about their release of the MaxDB extension for PHP.

A new MaxDB PHP extension has been released! Compared to the previous version that worked over php's odbc extension, the new driver offers good benefits. Firstly, the extension supports the MaxDB native interface, and thus delivers significantly better performance. Secondly the extension offers a broader feature set (which is mostly compatible to PHP's mysql and mysqli extensions) compared to the earlier driver's limited ODBC functionality.

[...] Today, the new PHP extention is available from our download section. In the coming weeks, the MaxDB client interface connecting to PHP will be adapted with the MySQL FLOSS license exception, and then you will be allowed to combine MaxDB and PHP with a broad range of other open source licenses.

And, for those wondering exactly what the MaxDB extension is good for: MaxDB is a heavy-duty, SAP-certified open source database for OLTP and OLAP usage which offers high reliablitity, availability, scalability and a very comprehensive feature set. It is targetted for large mySAP Business Suite environments and other applications that require maximum enterprise-level database functionality and complements the MySQL database server.