Side effects have made their Houdini software package available for free in an apprentice version.
The Apprentice Program gives you access to the same creative power used by the best animation professionals in the industry and provides a look at the latest Houdini work of companies like Electronic Arts, Sony Pictures Imageworks and Disney Feature Animation, among others.Equipped with a non-commercial edition, a CD full of documentation, easy-to-follow tutorials, online videos and sample files, you will quickly find yourself hooked on Houdini. The flexibility of Houdini's workflow makes it possible to pursue effects that you've been dreaming of.
The only limitations are in the renderer where it limits the rendering to 640x480 plus a watermark and a restriction to open but not save Houdini standard format. See the online FAQ for more details.
The edition is available for download (Australian mirror available) or a CD can be sent to you.
For download links and application forms see the Side Effects website.