Codemonkey76 points out that the listing is now on the US Xbox.com page right here. Interesting!
Remember when those Achievements for Mass Effect showed up online -- you know, these ones that mention Pinnacle Station? Well, the Swiss Xbox.com has offered up new details, pricing the DLC at 400 ($5) and billing it as a series of battle scenarios lasting around "2–3 hours." The Swiss Xbox.com listing says the DLC has been available since June 16, an obvious error.
So, Bioware, EA, would you just officially announce Pinnacle Station already?