To create a new account, click the "Register" link in the upper right or just click here. The "Register" link opens in a new tab / browser window so that you can easily get back to the community after registering.
Ok... when I click Post on this box, I was then asked to create a username as expected. Not sure why I was getting the full Cisco account creation wizard but now it's not happening. Maybe an issue when checking the SSO token first-time around?