Did the post your recieved happen to mention payment via a Cashier's Check or Bank Draft (or whatever they call it in your part of the world)? Here, in the U.S. I get this sort of message indicating payment was made with other than a PayPal account balance or credit card and it takes that long for the payment to clear.
In other words, the usual quick payment method is subverted, which is the reason I stipulate in my listings payment via PayPal only, SJ.
Having said that, you'll recieve yet another message from e-Bay indicating payment clearnace and it's now Ok to ship the item... (you haven't shipped it yet, have you?)