Great news from the Enthought Team! They are now offering a core version of their Enthought Python Distribution which is free for use and redistribution, as announced in their recent newsletter:
"We're also excited to tell you about a new support level for EPD, EPD Free. This lightweight distribution installs the essentials: SciPy, NumPy, IPython, matplotlib, Traits, & Chaco. While these libraries may not be enough for many current EPD users, we hope that the forever-free installer encourages more people to dive into Python. You are welcome to redistribute it as an environment for your applications, or pass it along to anyone who needs a simple scientific Python stack. "