basketSummary does not allways have the correct value. After adding a product to the cart the summary will not be updated. I'm using Firefox 1.0.5 and see this bug in the 0.3 and 0.2.5 versions of the cart.
Thats because I kept the plugin as simple as possible. This means that it 'plugs in' at the top of the code, where alll the other plugins go. At that point it works out what is in the basket. However, the code for adding products to the basket comes after this point, further down in the processing, so if you're on the basket page itself, then the basket summary may well be behind the times.
You can easily fix this by adding a redirect in orders.php. This will make the entire page refresh, thus the summary is updated.