Personally I'm against the "Art is Everything" definition of Art. Since, Giving art the definition of everything makes no progress towards actually identifying what is and isn't art. After all, if the world generally felt that Art was a synonym for Everything, then we wouldn't see so many critiques saying that a certain piece of work isn't Art.
I mean, I'm sure those who say that "Everything is Art" have felt the urge to claim that at least one piece they've seen in their lives wasn't or isn't Art before. That's why I see a need have a definition that separates art from everything, because it's natural to separate them.
Personally I define art to be anything that can be appreciated. What's good about this definition is that it allows for one person to consider something art, while another person can consider that exact same thing to not be art. Since different people appreciate things differently - So those that have experienced many things in their lives and can appreciate virtually everything would (With this definition)
define art to be everything. But, with this definition those who can't appreciate everything can actually say something isn't art (For them at-least). This definition also allows for several things to be considered art, (Science, Literature, Movies, Adds, Rhetoric, etc.) since most things in life can be appreciated.
For example, if I type the words: [Hi]. Most people (Including me) wouldn't consider the [Hi] to be art since they don't/can't appreciate the text or it's presentation. Most people would just see the good old Text. However, those who are experienced in making fonts might actually consider the [Hi] to be Art. Since they have experience in that field.
Changing my old example a little bit...
Now the image above is more likely to be considered art than just [Hi] because it brings the viewer into the central [Hi]. This natural feeling of being brought into the central [Hi] is easier to appreciate than the text by itself (Unless I screwed the image up with those black lines...
). Since it is, hopefully, easier to appreciate it should also be more likely to be considered art by someone. Same applies to the image that the original poster presented. Some can appreciate that painting, while others can't.
On a different note...
@DaBandito, Most (Not using the word "most" lightly) people consider Science an Art. Heck, I've got a book in my drawers called, "The Art of Problem Solving" that teaches anything from Algebra to Calculus. I'd say the book is fairly named and that Math has several uses in real life (Yay for related rates... >_<).
@Gorman, Out of curiosity, are you talking about yourself in the bathroom tile thing?
Hrm, after typing all of this up I realized my definition is pretty much hanz0's Definition...