Little update from Julie:
The ODK will be available to EVERYONE TONIGHT! She confirmed this via Twitter:

Me: @juhrman Hey Julie! One question: Will non-backers be able to download the ODK?
Julie: @einFluff Absolutely. The ODK is available to any game creator.
Me: @juhrman Thanks for your answer Just one mor: Will non-Backers get access to it TONIGHT when the dev site goes live?
Julie: @einFluff everyone and anyone.
Since the dev-site is protected by the usual sign-in, this could mean that the OUYA-Web SignUp will be opened to the public today (i am just guessing here...).

So, it's 4:35PM in germany, i'll have to wait till 9AM... I won't get much sleep tonight i guess....