I think it's important to point out that this picture is "correct" in that the lens was shifted correctly to keep verticals parallel, there's no barrel distortion or other lens-induced oddity, and, from what I can see here, everything is sharp and correctly exposed. This picture shows exactly what a very wide angle lens is designed to do. (I would only argue, Peter, that the sight lines suggest to me a slight downward, rather than upward, shift. Maybe there's no shift at all.)
But getting things right doesn't mean you get them the way you want. As others have pointed out, you might have moved the camera to the left, so your view of the rug would be more head-on and thus have less of the arrowhead effect. For an even neater trick, you could leave the camera where you have it, aim a bit to the right, then shift the lens left to get your composition back. You'll have roughly the same picture, but the rug will be squarer. The desk area will acquire some of the pointed geometry you don't like, but it can afford a little more "swoosh" before it becomes offensive.
What I have learned from fisheye lenses and panoramic photography is that
everything is a distortion. Wide angle views just make them more apparent. The wider your lenses and the more shift they can perform, the more often you'll confront these sorts of dilemmas.
So here's the short answer to your original question: Aim the camera a bit to the right and shift the lens a bit to the left to compensate. You could even aim your camera down slightly. Of course, this would violate the keep-the-verticals-vertical rule, but you have to pick your poison.
If you really want to read more of my nonsense on this:
http://www.michaelbaileyphoto.com/panos.htm click on "Notes"