Hi,
Joomla! 2.5 will be released in January 2012 and it is the successor of Joomla! 1.5. It will be a so called long term release and it will be the Joomla! state of the art until July 2013. The versions 1.6 and 1.7 were short term releases and they paved the way to Joomla! 2.5.
With Joomla! 2.5 it will be possible to run Joomla! on MySQL and Microsoft SQL Server. Drivers for PostgreSQL and Oracle seems to be very near.
Good luck!!!
