There was a time that Sun Microsytems was closely engaged in the GIS and LBS marketplaces selling workstations running Solaris-based solutions. Not so much anymore. MySQL supports spatial datatypes but they don't actively participate in the growth of the open source geospatial market like other open source solutions though many implementations exist. My attempts to contact them have always been rebuffed leading me to conclude that "spatial is not special" to them.
Now comes word that
Sun is buying MySQL. Sun has always pushed open source technology and now they have the "M" in the "LAMP" according to the press release, referring to Linux, Apache, MySQL, and PHP/Perl that is driving Web 2.0 initiatives. Don't expect Sun to all of a sudden become a force in the spatial business but they now have a very solid foundation to support the open source geospatial community if they wanted to.
http://code2code.net/DB_Linq/index.html
MySQL has been growing very fast and has been putting a lot of effort into making MySQL an enterprise level database. As such a lot of effort has recently gone into clustering, replication, stored procedures and other important features that were lacking when compared to Oracle, SQL Server, Postgres, etc.
In my opinion the merger with Sun is excellent news for MySQL (and Sun), as it will provide strong corporate/financial backing without losing the open source community contributions that have made MySQL grow so rapidly in the first place.