Ausiello reports:

"The show's currently shooting an episode for February sweeps that promises to make last year's turbocharged post-Super Bowl outing look like a stroll through Magic Garden. According to several sources, the action centers around a fire on a passenger ferry, and scenes were shot both on location along the Seattle waterfront as well as in Santa Anita, California. "It's going to be ginormous in terms of scope," reveals one spy, who says that more than 200 extras were employed for the disaster scenes"
and
"I've been hearing rumors about a major Grey's exit for months, but as of now they remain just that: rumors. Regarding Reaser, her role is still in the process of being conceived by Shonda Rhimes, and word on the set is that the shrink thing may not stick."

Something to one-up the bomb episode?! Woah! Can't wait for next month!