The April software updates have been released over the last few days. After you generate an activation code to log back in (seems like that always happens after updates, right?) you'll see some changes/additions/improvements.
Today we'll focus on one of the "top features" according to Salesforce: dynamic previews when sending from Salesforce CRM!
There is a new Marketing Cloud Connector* package that can be installed if you are currently using v5.0 or higher.