Well, our datacenter does use heat generated in server room to run heat pumps for our offices. Except there is much more heat in data center and we must still waste energy on cooling.

The premises nearby as far as I know were not much interested in harnessing this heat as that requires doing fair amount of infrastructure.

But I know that a nearby waste plant grows tomatoes and cucumbers by using electricity and heat from biogas (apparently when waste degrades it produces methane gas?!) - sorry for off-topic, just some green thinking went in my mind :)