Hopefully the financial woes of Dreamworks won't scuttle this...with the election of President Obama, there really won't be a better time to release this film, short of the 150th anniversary of the Civil War coming up in 2010.
EDIT
Just wanted to add I doubt it will cover the last two months of Lincoln's life. The war was pretty much a fait accompli by that point. More likely it will center on Lincoln's tortured decision to give the emancipation proclamation, and his inability to do so without a decisve Union victory, and all the behind the scenes and political wrangling over the decision to emancipate the slaves at all.
So my guess is that it covers the two months leading up to the battle of Gettysburgh, concluding with the Gettysburgh address followed by the Emancipation.
EDIT
Sorry, I love the Civil War.

Can you wrap your mind around Steven Spielberg directing combat action footage of the three days of Gettysburgh?