Webkit support for gradient transitions

Im wondering if anyone know when will webkit support transitions of gradients?
for example, the following code doesnt work in Chrome 6 (assuming grad-transition is a link):

.grad-transition {
     background-image: -webkit-gradient(linear, 0 0, 0 100%, from(white), to(black));
     -webkit-transition: background-image .5s;
}
.grad-transition:hover {
     background-image: -webkit-gradient(linear, 0 0, 0 100%, from(black), to(white));
}