I looked on the June Tailor website and didn't see one. Here is a link to the ruler section of their online store:
http://store.junetailor.com/store/c-2-rulers.aspx
If it's not on their website, I would assume they are no longer being made. You might be able to find one by doing an ISO (In Search Of) in the QB's Thrift Shop section, or on the SewItsForSale group at groups.yahoo.com -- or by checking eBay.
Edit: Okay. I found a page on the June Tailor website for this ruler, but the page is blank. Perhaps you could email them to ask about it:
http://store.junetailor.com/store/p-...-24-ruler.aspx
I *did* find the ruler as part of a kit available from Allbrands:
http://www.allbrands.com/products/52...11-x-23-cuttin
and the kit is even less at JoAnn's online:
http://www.joann.com/june-tailor-qui...a8QaAp318P8HAQ