Terraform is released under the GNU GPL and as such comes with full source code. You basically get everything I have. Terraform is available from it's home page http://www.peoplesoft.com/peoplepages/g/robert_gasch/terraform/ and possibly from other places such as the Sunsite gtkbuffet mirror and Linuxberg.
The rationale for using the GPL is simple: I have profitted enourmously (as has the entire Linux community) from the availability of free software that comes with source code. I wish for this process to continue and see the GPL as the mother of open source software licences which will assure the continued availablilty/openness of the source code.