This is just an overview of all the storage engines (for now the "special purpose" engines are missing) along with their license and expected release date (if not yet stable)

* MyISAM (GPL, bundled, stable)
* InnoDB (GPL, bundled, stable)
* Gemini (GPL, not bundled, stable or dead)
* PBXT (GPL, beta -> stable release Q3 2007)
* SolidDB ()
* ScaleDB ()
* NitroDB ()
* Falcon (GPL, bundled in 6.0, alpha -> stable release Q2 2008)