I'm the same. New Open Value Subscription agreement this year. As part of that we have Server Datacentre 2012 R2, but no KMS key issued with it - only MAK.
I've tried calling them and they say they are going to add the KMS key to my portal today sometime - but I'm not that hopeful.
Does anyone actually know if this KMS key is along the same lines at the KMS keys in the past? With it being a Server Group C which can activate Windows VL products?