Actually, the Cisco Learning Network has not fully relesed IOS on Unix. However, they have created an online offering that leverages IOU (IOS on Unix) and allows learners to access a real IOS interface. This crucial piece of the learning process is often difficult for entry level learners due to budgetary constraints. The new Cisco Learning Labs can be found over at the CLN Store .
Keith Barker, a top contributor and VIP of the Cisco Learning Network, put together this very good video that outlines many of the features of this new offerings.
I certainly think this is a step in the right direction for Cisco. It at least shows that they are listening to us to a degree. Greg Ferro over at the Etherealmind Blog even had a petition to try to get Cisco to have an officially sanctioned IOS for non production use. Is the current offering the only step that Cisco should take? Absolutely not. I really think Cisco, as a company, would benefit from being even more open to the idea of non production equipment and software. One main issue is obviously learning. However, corporations also struggle with legal and/or viable methods of testing changes prior to placing them in production.