I'd like to know details about her departure, too.
I'm curious as to why she left. I know it was partly because of that other movie, but that was just a 2 parter, she could have come back.
So the question remains, did she want to leave? Did she plan on coming back? Did TPTB not want her anymore?
And, most of all I'd like to know why the writers didn't explain Sofia's whereabouts. Would it have been so hard to write that one line in? She could have told someone that she was transferring, or going on a long vacation, or whatever. But no, her leaving wasn't even acknowledged! Nobody seemed to miss her at all! I wouldn't have expected a lengthy explanation, but one single conversation between her and Brass or even Grissom shouldn't have hurt.
If I were invested enough I'd write a mail to CBS, but I wouldn't know who to ask, and I don't expect them to care enough to reply anyway... oh well, it's just another forgotten storyline on a dying tv show...