For everyone that's missing the MySQL support in the new PHP 5 Beta that has been released, you might take a look at the new addition to the "preloaded extensions" family - SQLite. And PHPEverywhere has a new piece this morning on their look at it.

SQLite has been ported to work with PHP. I have been testing it for the past few days and it works well. I have also created an ADOdb driver for SQLite. Now I can imagine that SQLite will make it much easier for developers to distribute pre-packaged, ready-to-run PHP apps. A lot of cheapniks will install it on their shared hosting servers too. But a word of caution, though SQLite is really powerful for such a tiny package, SQLite is really a battlecruiser. Let me explain...

He goes on to talk about how SQLite, while fast and easy to use, can still be a pain when used incorrectly. There's even a debate going on over on the php-internals mailing list about the pros and cons of SQLite.