The Lightning developer guide says that an aura:attribute can contain a List of custom apex type objects, like this:
<aura:attribute name="colorPalette" type="List<docSampleNamespace.Color>" />
However, when I try this, I get this error message:
Message: The value of attribute "type" associated with an element type "null" must not contain the '<' character.: Source
Is this just not implemented yet in the dev preview, or am I doing something wrong?