Getting the Aiptek T-6000U tablet working with Ubuntu 9.04 was relatively easy, following the directions here.

Summary:
Install the xserver-xorg-input-aiptek package.
Add a file called 10-aiptek.fdi to the /etc/hal/fdi/policy directory containing:

<?xml version="1.0" encoding="UTF-8"?> 
<deviceinfo version="0.2">
  <device>
    <match key="info.product" contains="Aiptek">

      <merge key="input.x11_driver" type="string">aiptek</merge>
      <merge key="input.x11_options.SendCoreEvents" type="string">true </merge>
      <merge key="input.x11_options.USB" type="string">On</merge>
      <merge key="input.x11_options.Type" type="string">stylus</merge>

      <merge key="input.x11_options.Mode" type="string">absolute</merge>
    </match>
  </device>
</deviceinfo>