Is there some proof of this outside of this USA Today article?

I came here with the exact same concern as the GP comment.

“We’ll continue to have Internet Explorer, but we’ll also have a new browser called Project Spartan..."

It just reeks of marketing double-speak that gets engineers excited, only to find out that they're stuck maintaining code for N + 1 browsers now.

Incidentally, Microsoft rebranding exercises infuriate me. Arguably, Spartan is a "new" product, but by that measure any product rewrite should get a completely new, unrelated name rather than a version number. I remember COM + DispInterfaces ==> ActiveX, Outlook Express ==> MSN Messenger, MSN ==> Bing. It's just irritating and confusing to both developers and consumers.