You probably need to create an mc_config_inc.php in the soap api path (there is mc_config_defaults_inc.php to use as a template). There is a configuration option to select the minimum user threshold needed to have access to the SOAP API. Lowering this to VIEWER should be sufficient.

Ok, that does the trick.
Maybe you should think about setting VIEWER as standard for read operations. It would be more intuitive.

I think the reason for it's current default setting is that it prevents anonymous accounts from being able to abuse the SOAP service. By instead requiring reporter access, which is the default access level for new accounts, it at least requires someone to have taken the step to register an account before getting access to the API.

Hmm maybe you could block the soap api for anonymous users... But this is your thing, you have the greater view ;)

As this was a configuration issue, I'll close it. The real issue will be tracked under bug 0012328 , but for version 1.3 , as it is a large change.