That cryptic Gamestop product page of yesterday? The one proclaiming a previously-unannounced Knights of the White Stallion expansion?

Bunk.

Quoth Peter Hines, V.P. Of Marketing and Public Relations of Bethesda:

There's no expansion in development called Knights of the White Stallion. That's the name of a quest in Oblivion.

Right now we have no announced plans for any new content, add-ons, or expansions. If that changes, we'll let folks know.

That's an emphatic worded denial if we ever heard one. Panties unbunched, gentlemen. Florian Eckhardt

GR News: Pete Hines From Bethesda Says No Oblivion Expansion [Gamers Reports]