Here are some really rough numbers derived from pausing the live stream.

Falcon Heavy Side Booster Separation - 61km, 6,881 km/hr

Falcon Heavy Core 1st Stage Separation - 92.5km, 9,474 km/hr

Also a link to screen caps of speeds/altitudes of previous Falcon 9 separations

http://www.planetary.org/multimedia/space-images/charts/falc...