We are compatible up to a certain release that's over a year old, so their latest developed library isn't compatible.
Blackcoin recently ported bitcore (web development - javascript library)
Well, we'd still need to get blockstack to integrate Gridcoin or we would have to do the work ourselves (no other alt has support yet, but they've stated previously they were interested in making it blockchain agnostic).
use case(s):
further info:
current situation (via @grctest):