I guess you missed the promos, news reports and articles that have been covering this for the past 2 months+. WHDH is no longer affiliated with NBC as of today and is now independent.
Boston's new NBC affiliate is WBTS. It's kind of complicated over the air:
WBTSLD 8-1 (RF 46) - 101517 (A low power signal that mostly only available in Boston and the outskirts of the city)
WNEUDT2 60-2 (RF 34) - 75068 (Based in Merrimack, New Hamsphire, mostly only available in the northern suburbs)
It's also on 60-5 (RF 18), via WMFP's over the air signal which covers the rest of the Boston market, but they need to notify Gracenote with the details since it's still not included on the local lineups. You can file a ticket to help the process, but be sure to specify that it's coming from WMFP's digital signal so they add it to all the local lineups that have WMFP with WMFP's RF number 18, and don't incorrectly create it with WNEU's RF number and only add it to the local lineups that get WNEU.
On cable its position varies. Dish, DirecTV and Comcast have it on channel 10, it's number for FiOS, RCN and cable providers outside of the city of Boston vary.