I put up a post on the bug section of the WoW forums here but wanted to ask around and see if anyone else had noticed this.
While testing my new spec/abilities in Karazhan last night I noticed that my Shadow Word: Pain was not scaling with non-self buffs.
Ie. It didn't scale with Curse of Elements, and most noticeably it wasn't scaling while I stood in the blue beam on Netherspite (which should have been the most obvious place it increased in damage, VT + devouring plague were ticking up around 2k by the end of the fight, and SWP hadn't moved from 620'ish damage for the whole fight).
It did seem to scale with Shadow Weaving fine, but that was the only thing that seemed to modify the damage of my SWP ticks.
Furthermore, I found that it would often seem to 'drop' from the mob I applied it to when my Mind Flay was cast. It didn't occur all the time, but that could be because I went 2/3 into the 'Pain and Suffering' talent for 66% chance for Mind Flay to refresh Shadow Word: Pain.