The Custom Layout Manager is a 1.0 version of a Lead Card in my opinion. A 2.0 version would be where you can group fields, like in Salesforce.com (e.g. score field group, contact details). But 3.0 would a proper Lead Card, like many competitors have.
A Lead Card is a nice visual overview of the lead. It has a picture (obtained from social), last 3 activities, last 3 emails, last 3 successes, some company segmentation details, contact details, perhaps some pending tasks (from SFDC), You can quickly do Lead Actions on it. You can also see opportunities. And you can open an overview with all programs the lead is a member of. Would also be nice to see if there are any scheduled emails for the lead.
@Development: I'd be happy to help if this makes it on the roadmap!
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