On July 9, 2008, Drupal released versions 5.9 and 6.3 fixing some of the security vulnerabilities found in the code. Apart from the security vulnerabilities it also fixes some of the bugs that were reported.

Here is a question – what be the version of next release in 5.x series? 5.9 is out ..and 6.0 has been out a long time back. [edit: Duh! I was thinking math ... the next version is 5.10 .. simple ]