From SVU’s production blog latest entry which was a twofer – announcing the return of Mariska and a cam-phone ‘razzi style photo of Stephanie March doing her thing:

Quick, let’s all speculate – is that Jack McCoy’s office? Who else could it be? Perhaps she’s in Judge Donnelly’s office? Man, she looks hot in that suit.
OK, so that last one wasn’t so much speculating as it was a foregone conclusion. teehee.
The BAD NEWS: According to the blog, the first eps to feature Ms. March will air March 10th and not, as previously reported, on February 17th.