there is a really great line that I use when something like this happens, but it is just toooooo darn good to share with all these people.... sorry guys
no, don't call her the next day, that's for sure. what I do usually do though is really make sure she is going to show up, drill her. say something like, "you're going to be there right?" or "you know, I really don't like flakes, you're not going to flake out are you?" and have a very serious, almost lecturing look on your face, it puts her in her place, and gives her a chance to fess up if she was going to. at which time you say, you know, i'm not even interested anymore.
now, for the flaking on a date thing.... I honestly don't get many of those, that may be because of what I just said above. but you could call her or write her and say "what did you're cat get sick and you had to see your great great grandma in the hospital? what's your deal? you could of at least been enough of a human being to pick up the phone and tell me you wouldn't be there."
something like that... I like my personal line better, that that may work.
Basically, what you want to do is let her know in a direct, serious, not quite mean but honest way that what she did was immensly rude, and that any person with the slightest bit of decency would of a) shown up, or b) called and said she couldn't show up