Updated April 3, 2012
This currently affects up to OpenCart 188.8.131.52.1; the availability attribute was added in 1.5.2.x (March 3rd, 2012 Release).
However, other issues, such as reporting all item conditions as "new" and Google Wallet not deducting inventory (which PrestaShop and Magento have been able to do for a while) still exist. However, it finally has IP Ban! Of course, if your web host provider has a tool to manage IPs, such as cPanel, it probably isn't a significant addition.