It all started with this teaser image for an upcoming CAPCOM / SEGA / Namco Bandai crossover RPG game on the Nintendo 3DS called "Project X (pronounced "Cross") Zone (プロジェクト クロスゾーン):
See the image over the "G" in SEGA? That was widely speculated to be Gemini Sunrise's "Chromosomes" in the 8 Bit DNA lineup. Oogami Ichiro was also speculated to be in it.
Flash forward to the 12th, and official confirmation of Sakura Taisen's representation comes to light in Famitsu Magazine:
(Notice Chattes Noires at the bottom)
While there was no announcement of Gemini in the roster (

), scuttlebutt has it the full roster has not been released, and it's more than likely (given the teaser) she will be announced later, perhaps as a team with Shinjiro.
There have also been publicity shots released of both Sakura and Oogami:
More details will be released on the Project X
website on the 17th. We'll keep you posted!