Lost Feature - Zebra Striping Blocks

When I upgraded from 6 beta2 to 6 beta3 I lost the odd and even classes to my blocks that I was using on a sub-theme. Simply downgrading to beta2 makes things work again.

Here's an example of the css I was using that doesn't work anymore:

#sidebar-left .block.even
{
background: url(images/green-bottom.png) bottom right no-repeat;
}

#sidebar-left .block.odd
{
background: url(images/blue-bottom.png) bottom right no-repeat;
}

#sidebar-left .odd .block-inner
{
background: url(images/blue-side.png) top right no-repeat;
}
#sidebar-left .even .block-inner
{
background: url(images/green-side.png) top right no-repeat;
}

#sidebar-left .odd .block-inner h2,
#sidebar-left .odd .block-inner .content
{
background: #003399;
}

#sidebar-left .even .block-inner h2,
#sidebar-left .even .block-inner .content
{
background: #006600;
}