Database Servers
Fedora includes both the MySQL and PostgreSQL database servers.
The Fedora release notes are a collective effort of dozens of people. You can contribute by editing the wiki page that corresponds to this part of the release notes.
mysql
MySQL has been updated to 5.1.x. This represents a major version upgrade from Fedora 10's 5.0.x release series. You should test database-using applications for possible incompatibilities. Upstream's release notes can be found at [1].
If you are upgrading a Fedora 10 installation that includes a live 5.0.x MySQL database, don't forget to run mysql_upgrade after completing the software upgrade. There is a report that this may fail altogether if the 5.0.x database had been updated from an even older installation without running mysql_upgrade at the time. If you think this might be the case for your database, it is prudent to run mysql_upgrade on the Fedora 10 installation before upgrading. (And, of course, you should have backups if the database content is at all critical.)
postgresql
Fedora 11 includes version 8.3.6 of postgreSQL.
A dump/restore is not required for those running 8.3.X. However, it is recommended to REINDEX all GiST indexes after the upgrade.