I took the D-Line in from Reservoir Station. The first train that came through was the most packed I have ever seen a Green Line Trolley. This is saying alot, as I have been in some tight spots on the Green Line. However, before this train even left, an announcement came over the loud speaker at Reservoir (I've never heard this used by a live person in the 3 years I've been using the station) that trains were boarding on the third platform at Reservoir. It seems that they were boarding new inbound trains direct from the Reservoir yard all morning.
The return trip was much more crowded. I waited for about 10 minutes at Hynes for a D-train that I could actually board, with no luck. However, trains were entering the station about every minute or so. Eventually, I gave up and just got on a C-Line train.
I have to say, overall I was very impressed with how the T handled the extra crowds. As someone joked on a different thread, I wouldn't have been the least bit suprised if they closed the entire Green Line for service, and resorted to bustitution. For once, the T pleasantly suprised me.