It allowed me in to at least test out the interface, where I was able to determine that some of the pretty stuff on the home page (autoscaling, for example) doesn't seem to be available yet.
RDS support is coming soon (approximately one month) and ELB support to be added shortly after that. AutoScaling and Availability Zones are both high priority, but we have very limited resources and I can't commit to a timeframe at the moment.
Thanks for creating IAM credentials and trying us out. If you have any suggestions on how to improved credential handling, please let me know.