According to 9to5mac it is possible to have 4 finger gestures on a Penryn Macbook Pro with the beta of Snow Leopard and without any do-it-yourself fudging.
If the thing is confirmed with the final version (we live in hope) it will be a small present made to those who thought Apple incapable of doing this to customers who have already bought a product.
This is perhaps also the way found Apple to activate this function without having to do it via a specific paying update as it was the case for the activation of the 802.11n because of the Sarbanes-Oxley law.
[translation by crispin]
