I'm almost positive that this is a classpath problem.  However, why?
Shouldn't "apt-get libmysql-java" set the classpath for netbeans?

How do I know what the problem is?

When run, it's indicating that it's using com.mysql.jdbc.Driver, so
doesn't that indicate that the classpath is fine?

I'm following the manual at:

https://help.ubuntu.com/community/JDBCAndMySQL

Possibly it's because I'm running ubuntu 8, but this seems unlikely.  
This example code is almost exactly as what I've seen elsewhere.

init:
deps-jar:
compile:
run:
com.mysql.jdbc.Driver
Exception in thread "main" java.lang.ClassNotFoundException:
com.mysql.jdbc.Driver
       at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
       at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
       at java.lang.Class.forName0(Native Method)
       at java.lang.Class.forName(Class.java:169)
       at a00720398.DBDemo.main(DBDemo.java:24)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

thufir@arrakis:~$ cat NetBeansProjects/ubuntu-jdbc/src/a00720398/
DBDemo.java
package a00720398;

import java.sql.*;
import java.util.Properties;

public class DBDemo
{
 // The JDBC Connector Class.
 private static final String dbClassName = "com.mysql.jdbc.Driver";

 // Connection string. emotherearth is the database the program
 // is connecting to. You can include user and password after this
 // by adding (say) ?user=paulr&password=paulr. Not recommended!

 private static final String CONNECTION =
                         "jdbc:mysql://127.0.0.1/emotherearth";

 public static void main(String[] args) throws
                            ClassNotFoundException,SQLException
 {
   System.out.println(dbClassName);
   // Class.forName(xxx) loads the jdbc classes and
   // creates a drivermanager class factory
   Class.forName(dbClassName);              

    //ClassNotFoundException:com.mysql.jdbc.Driver

   // Properties for user and password. Here the user and password are
both 'paulr'
   Properties p = new Properties();
   p.put("user","java");
   p.put("password","password");

   // Now try to connect
   Connection c = DriverManager.getConnection(CONNECTION,p);

   System.out.println("It works !");
   c.close();
   }
}
thufir@arrakis:~$
thufir@arrakis:~$ ll /usr/share/java/mysql-connector-java.jar
lrwxrwxrwx 1 root root 30 2008-07-02 17:10 /usr/share/java/mysql-
connector-java.jar -> mysql-connector-java-5.1.5.jar
thufir@arrakis:~$
thufir@arrakis:~$ java -version
java version "1.6.0_06"
Java(TM) SE Runtime Environment (build 1.6.0_06-b02)
Java HotSpot(TM) Client VM (build 10.0-b22, mixed mode, sharing)
thufir@arrakis:~$
thufir@arrakis:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04"
thufir@arrakis:~$

thanks,

Thufir