No, probably not. I wanted to quell this rumor before it starts. A new item showed up in WoWhead's beta database: Certificate of Ownership. This is an item created through the new Inscription profession. While the text says, "Allows you to rename your pet," we'd bet dollars to donuts (mmmm... donuts) that they're talking about renaming hunter pets.
Aside from the large amount of work on the part of Blizzard developers to implement companion naming, we have another reason to believe this item won't effect vanity pets. Blizzard recently updated their official Small Pets page and the very first bullet under Other Information states very clearly that small pets cannot be renamed. You also might notice that Blizzard was kind enough to provide a link back to this site for additional info (Yay!)
The new official Small Pets page also states that players can hit "Shift-P" to open up their pet tab. I imagine that's a shortcut quite a few of us will be using in the near future.
September 11, 2008