Sideshow Collectibles has updated their "ask Sideshow" page with a revelation for 2010, the 1st female 12" G.I. Joe figure(s)! Here's what they had to say:

Q: Any ideas on when we will see female G.I. Joe characters in Sideshow’s 12 inch-line? Any hints on who they may be?

A: You could probably guess who, but we expect that the first female figure(s) will be revealed within 2010 and released in 2011.

So who could the first figure, or figures be? The Baroness? Cover Girl? Scarlett? Zaranna? Jinx? *UPDATE!*:

Q:
I have been loving the 1/6 G.I. Joe line, and am very excited about the
upcoming dios and hopefully very soon Premium Formatss. I was
wondering, how soon can we expect the Baroness in any form? She is one
of my favorites, and haven’t gotten a decent collectible of her since
Palisades did the bust so many years ago. And, while I am on the
subject, how soon for any females in the Joe line for that matter? I
know there isn’t a lot to go around, but we need some ladies!!

A: Baroness
is not yet planned for the diorama line, but she is planned for every
other format to be utilized for GI Joe. You will see some Joe universe
females revealed in 2010.