Split screen multiplayer has been confirmed for BWII.
"Some of you may of played the original, but you couldn’t help but feel how great a multi-player mode would of made the game. Well Kuju thought that too. But, not only have they added split screen multiplayer, they’ve added full online play as well. There are three different modes to choose from, these include Assault (which is just an all out standard war), Skirmish (much more tactical than assault and with smaller armies) and finally Co-Op (work with friends) - I’ll go into more detail for each mode below."
If you need more proof then here it is: http://wii.nintendo.com/site/battalionwars2
At the bottom right there is a wiimote with a 2 on it meaning it is 2 player.