Many artistic computer-technology developments have been the result of human desire to create that which does not exist. The Graphical User Interface was one such development that turned computers from typewriting calculators to self-painting canvases. This is not to say that the GUI was strictly an art-related development, but that depends on your definition of art. According to Wikipedia–the God of the collective knowledge of the human race–art is "the process or product of deliberately arranging elements in a way that appeals to the senses or emotions." According to this definition, the GUI is art in that it deliberately processes technologically coded informational elements and produces an interface appealing to our senses and/or emotions. Other definitions of art require that the product have no function except to act as art, which would not include the GUI.
But whether or not the GUI is art is not an issue (thanks for reading the intro paragraph though!), what is important is that computers now have the ability to create and display art in a way many humans find appealing to their senses. Computers aren't creative–they don't chose which paints to apply where, based on their personal tastes–but they are productive; they produce both the process and product of new media art.
During the Cubist and Dadaist reformations of the definition of art, artists like Pablo Picasso and Marcel Duchamp explored assemblage as a new option for the artistic process and product. They were using relatively new technologies like the photograph to create brand new compositions, most likely on a quest for the non-preexistent content Manovich references above. Similarly, in the late 1950's musicians started experimenting with using new audio recording technologies as a creative tool. In 1961, John Tenney made a song called "Collage #1 ('Blue Suede')" by editing together different parts and sounds from a recording of Elvis Presley's "Blue Suede Shoes". Now, software like Adobe Photoshop and Apple Logic have turned Picasso's, Duchamp's, and Tenney's complicated visual and musical compositions into commonplace child's play.
What now is non-preexistent? Does the GUI and computer open endless doors for creation, or instead destroy the options for desirable creativity by making everything possible? Children's jaws don't drop as easily in the movie theatre as they may have when clay-mation explosions were commonplace instead of CGI ("computer generated graphics" or graphics generated by a computer). While the medium of media art (which I would argue is related to software) continues to improve, so does the canvas (or hardware). As Apple's Final Cut Pro is upgraded to edit HD video ("high definition" video with definition that is high), hardware is improved to play HD footage, such as LED screens ("light emitting diode" screens where diodes emit light), and ultimately the overall experience is improved with new never-before had possibilities. New game consoles outdate their predecessors with promises for more realistic graphics, faster speeds, and new revolutionary features (i.e. motion sensors and virtual goggles) to help improve the overall sensual experience. In music art, programs like Apple's Logic and Digidesign's Pro Tools make it possible for musicians without formal training in any given instrument the ability to create sounds from them. Some see this as a horrible travesty, destroying all the ideals and standards of what good music is. I would argue rather that it breaks down walls limiting the definition of music, and encourages humans to find new ways to explore with the new tools we have been given. But in a world where anything can be created visually and audibly using the computer, what is the next big media revolution going to be? Stone tablets were outdated by papyrus and paper which has been outdated by video screens and eventually touchscreen GUIs. But what could possibly be more technologically artistic and sweetass than an iPad?