Update: Never mind. Ben Jones, one of the B&B producers, said the Empress "news" stems from a false report. Disregard what you read below. These aren't the droids you're looking for. Move along, move along.
Via LegionWorld I found this on World's Finest:
The World's Finest has obtained the updated character roster for the upcoming Batman: The Brave and The Bold animated series.
Below is the updated list of characters scheduled to appear on Batman: The Brave and The Bold alongside Batman, in alphabetical order and divided by status.
On the list is the Emerald Empress.
That's all I know so far.