Side Effects Software has released an update to Houdini Apprentice, the evaluation version of their 3D modeling and animation software. Apprentice is essentially the same as the full fledged product, but with the limitation of a non-standard file format and watermarked renderer.
More information on the release can be found at the Side Effects Software website. CD images which include the IRIX version of Houdini Apprentice 6 as well as tutorials can be found at the official mirror:

