Japanese retailers, specifically Amazon Japan and Yodobashi, appear to be fresh out of Vita preorder stock according to online listings.
RPG Site noticed that the two retailers were both listing on their Vita pages that the items are unavailable or out of stock.
Apparently, users who attempt to order either the 3G or WiFi enabled versions of Vita are met with a message saying that stock is no longer available.
Other retailers are also selling out as well including Sofmap, Bic Camera and Joshin. This could be bad news for American gamers who were hoping to import a Japanese PS Vita at launch (especially since they'll have no chance to go down to the store on launch day,) although it is certainly good news for Sony who is facing large amounts of skepticism about Vita's chances of surviving in a gaming market now flooded with very capable smartphones.