I'll hunt one down. From memory it was bomberman style enhancements because time bomb stuck in my mind looking at the tree. I'll edit in with a link if I can find it. There wasn't much discussion on that one. There didn't seem to be a lot of interest compared to monks, assassins, and acrobats.
EDIT:
http://forums.ddo.com/showthread.php?t=394938 had a bit of discussion on it. I didn't see anyone make a "rough-in mechanic" like Trekna did with henshin, acrobat, and assassin. I posted a few things from the leaked tree in a couple of threads but the most were in the posted thread. I didn't notice a dev comment on the mechanic tree.
Some highlights on at the time: time bomb, kills switch, wand and scroll mastery.
At that time all 3 rogue trees were up, henshin, part of ninja spy and there was a comment on shortswords regarding ninja spy, a large portion of war chanter, and the spellsinger tree.
EDIT2: Also, we had confirmation those trees were outdated when we received access to them so a person needs an extra large salt shaker for the grains taken with the posted trees. A lot of what we saw were more like a glimpse of the features but not a good representation of where they were at.