In the release notes liked above, it has the following:
Lead Map REST API
Marketo now supports the use of email-disposition fields over the Lead APIs (includes Black Listed, Marketing Suspended, Email Suspended, and Relative Urgency).
What does this mean exactly? I think it might mean we will be able to get these fields when querying a lead. They don't show up in lead/describe.json (release date isn't until October 12 so that makes sense) so I'm not sure what they mean exactly.