From someone else on another forum, United is still having reliability issues:
N27901 was showing a 3hr delay out of IAH then got canx, apparently due to an electrical issue N26902 had all its flights cancelled today and hasn't flown since Friday N27903 departed IAH after a 30m servicing delay N20904 had its return flight from DEN cancelled N45905 has been stuck at LAX since Thursday N26906 had all its flights substituted by 767/777 today
Looks like United has restarted International flights. I see N260904 operating the Denver-Tokyo flight now. That means all airlines with the 787, prior to the grounding have now re-started international flights.