I'm excited, too! I always (when I'm dieting) check the calories online before I go somewhere to make sure I'm "allowed" to have something. It'll make it easier to see it up there.
As for accuracy, studies show they tend to be inaccurate but provide a decent gauge. They seem to fall fairly close the actual.
Here's a comparison of restaurant posted values and actual values:http://www.kypost.com/content/themen...s/default.aspx
And a couple of articles on it: