Nginx, yes. At least the dev versions, as older versions have it as spdy configured. Apache not yet, but you can use its e.g. by modifying the master template when your apache supports it.
I guess there are too many server systems out there that do not support http/2 yet and we would break their setups if we make it the default. But we will add an option to enable it for apache as well.
I think this should already be available in Sites > Website / Subdomain (vhost) / Aliasdomain (vhost) > SSL Tab.