The one she had in her suitcase is gone, but there's another one at home. Call Ned and ask him to find it for you.
After a couple of minutes, Ned calls back; he was caught by Carson, who's hopping mad. After he calms down, he agrees to send the poem, which you'll find taped to the door of your hotel room the next time you go there. So what do we do with it?
Well, figuring out what it means will take you most of the rest of the game, since Kate used it to disguise one of the most critical elements of the Colony Operation. You'll pick up bits and pieces of it as you go along.
As a general rule, any message you find from Kate that quotes the poem, or indeed anything from "Alice in Wonderland," is worth paying close attention to.
Other than that, just carry the poem around and wait for further instructions. As I said, you won't really decipher it till you're almost at the end of the game.