Comment 1 for bug 315314

For a quick work-around, extract tomcat-dbcp.jar from the base Tomcat 6.0.18 distribution from Apache, and place it under /usr/share/tomcat6/lib. Also remove the symbolic links to commons-dbcp.jar and commons-pool.jar from this directory.
Please note that the Ubuntu 8.10 Tomcat6 distribution is completely hosed; you must place the JDBC driver jar into /usr/share/tomcat6/lib directory for it to be found, NOT, as you would think, in the /var/lib/tomcat6/lib directory. It seems like the 8.10 Tomcat6 distribution ignores this directory when building the classpath!