Innobase is the Finnish company which developed the InnoDB engine for MySQL. InnoDB brought MySQL many of the features necessary for deployment in non-trivial installations, including support for transactions, row-level locking, and foreign key constraints. These are some of the features that would allow MySQL to be used in place of a commercial database such as Oracle. With the imminent release of MySQL 5.0, which includes support for stored procedures, triggers, and views, even more applications could be built on MySQL.
One of the main features in which Oracle beats out MySQL is in clustering. MySQL's clustering, the NDB engine is stil rather immature, and from what I understand, not having ever used Oracle, it has some nifty clustering. I'm sure that it has some other cool features that I've heard of. So, are we likely to see some Oracle technology make it's way into MySQL? Or more pressure to purchase licenses where they aren't needed?
The state is that great fiction by which everyone tries to live at the expense of everyone else. - Frederic Bastiat