symfony 1.4.19 has just been released.
Here are all the changes from the CHANGELOG:
-  fixed sfPDOSessionStorage for Oracle (closes #10022)
-  fixed sfWebRequest::splitHttpAcceptHeader incorrect result order (closes #10069, patch by Keri Henare)
-  fixed exception format when using the PHP 5.4 built-in server (closes #10067, based on a patch from jgskin)
-  fixed sfPDODatabase::call() method (closes #10044)
If you've checked out a copy of the tag from Subversion you can switch to the latest version:
$ svn switch http://svn.symfony-project.com/tags/RELEASE_1_4_19
If you are using the PEAR package you can update using the pear command:
$ pear upgrade symfony/symfony-1.4.19
And as always, don't forget to clear your cache after upgrading.