haven't seen any announcement but it appears that message boards will less than some threshold of posting activity are being shut down. I can access all the more active ones but get an error message for those boards which have not been so active. Looks like even PAA and SXL have lost their message boards.
NGLS too, along with many smaller MLPs. Unfortunately this means the the boards being retained are the ones with the high amount of garbage posting. The ones with a small volume of serious posts are being taken down. Garbage wins again.