Here's the original announcement http://pages2.ebay.com.au/Hub/May_2012_seller_changes/Boost_your_sales/Multi_variation

 I'd say the link for the tool is appearing on everyone's selling summary, but if you click the link it will probably tell you that you have no listings to merge. I sell clothes but all my multi-quantity variations are already using the format, so it's telling me I can't merge any. 

On a side note, it doesn't look like the variant format has been rolled out to any other categories, either. 😕