Great plugin, very easy to use. I have a problem with the session.
I can view products and add them to cart from wp and see them in magento. But if I show a block with the cart in it (in wp) no products. The block shows the products ok in magento.
I see you are calling getSingleton and multiple products go to the cart from wp so I know sessions are working.
If I use the_block and go for the cart_sidebar I get the error previously reported by twistedindustries.
Should it be able to show the cart?