Meryl Streep and Carey Mulligan are definitely in for the SAG Awards' best actress category, the former for her London student in An Education, the latter for her Julia Child in Julie & Julia. The other three slots are a little more iffy.

I believe Sandra Bullock will get her first best actress SAG nod for her conservative matriarch who adopts an inner-city teen in the surprise fall hit The Blind Side. Bullock has been around for quite a while, and this was her second major hit of 2009 (following The Proposal). And this year she's proven she can do comedy and drama and earn millions, and that's no small feat (especially the millions part).

Helen Mirren = prestige and class. Those are always good qualities when it comes to film awards. Mirren did get a best actress – drama Golden Globe nomination and The Last Station did quite well at the Spirit Awards, so her performance has surely been noticed. Gabourey Sidibe is, along with Carey Mulligan, the female newcomer of the year. Considering that Precious is bound to get a best ensemble SAG nod, I believe it's fair to say that Sidibe will get her own personal nomination since she's at the core of that film. That said…

Any of the three "strong possibilities" may take the place of one or more of the three aforementioned actresses. And the same goes for even the actresses listed as "possibilities," as they all have strong roles that have been well-received and/or have earned them award recognition, e.g., Catalina Saavedra at the Gothams (though the fact that the film is in Spanish works against her), Abbie Cornish received a best actress nomination from the Chicago Film Critics, Michelle Monaghan won in San Diego, etc.

Penélope Cruz would have a better chance for her role in Broken Embraces if this were the Oscars, but SAG nomination voters tend to shy away from non-English-language films. (Academy members have the same issue with subtitled performances, but it's less intense.)

And despite her Golden Globe nomination, I don't believe Julia Roberts has a chance for Duplicity.

Strong possibilities:

Saoirse Ronan, The Lovely Bones

Marion Cotillard, Nine

Emily Blunt, The Young Victoria

Possibilities:

Abbie Cornish, Bright Star (above, with Ben Whishaw)

Michelle Pfeiffer, Chéri

Zooey Deschanel, (500) Days of Summer

Michelle Monaghan, Trucker

Natalie Portman, Brothers

Catalina Saavedra, The Maid

Maria Bello, Downloading Nancy

Less likely:

Penélope Cruz, Broken Embraces

Sandra Bullock, The Proposal

Meryl Streep, It’s Complicated

Renee Zellweger, My One and Only

Amy Adams, Julie & Julia

Audrey Tautou, Coco Before Chanel

Hilary Swank, Amelia

Maya Rudolph, Away We Go

Rachel Weisz, The Lovely Bones