Egads, I saw your message when I was browsing at lunch, figured I would respond after work (that's why they call it work) - looks like the thread sparked off something.
In response to the question when does digital photography become digital art, I would argue (almost) all of it is. Same way as almost all film photography is art. Just don't ask me what art is. Most of the images I do (and presumably most of those done by those who hang out here) are designed to be aesthetically pleasing or to invoke a reaction from the viewer. Whether I succeed or not is another question, but this is the goal at least. So if I'm photographing a part of the environment, I manipulate the image by photographing a selective part of the environment from a likewise selected vantage point to achieve a pleasing (or whatever) effect, select a time of day to give me the right light. I then use a medium that I think will best capture the image (digital, a specific film), modifying the image with filters. And finally do global and specific digital manipulations in Picture Window or Photoshop. I still consider it art (digital or otherwise), whether I have done no post-processing at all or whether I have cloned something in or out.
That being said, for things I display, I have cloned things out (telephone wires, annoying streetlights, etc), but I've never put things in that weren't in the image originally. In the things that I have cloned out, it is (usually) because I had no choice to have the object in the field of view and still get the shot. So far at least, my pleasure in photography has been to represent things that were actually in my field of view (otherwise, why not set up a stock of useful image parts and take up digital compositing). And, of the things where I know that something has been inserted, and can't say that I have particularly liked the image - but if I can see that they've done it, they can't have done a very good job.
Mind you, if the goal of the photography is an accurate record of events - then all this goes out the window.
So, I must admit, I have no clue when a photograph (digital or otherwise) ceases to become a photograph - although there have been a lot of interesting thoughts in these two threads. But let me ask a only partially hypothetical example - I saw a photographer at a craft show proudly displaying a photo entitled something along the lines of Chincoteague Pony. Showed a lovely sleek pony on the beach, head up, looking majestic, mane flowing beautifully in the wind. Only problem, is I've spent enough time in Assateague and Chincoteague to know that it wasn't a Chincoteague pony. It was well groomed, and didn't have the wide girth associated with grazing in brackish water. So, if I took a nice beach scene, and cloned in a Chincoteague pony into it (and did it just so, so that you couldn't tell they were photographed separately), would this be any better, worse, or even different?
It would take a better mind than mine to say.
As to being lazy with digital, to tell you the truth, I *believe* my technique has actually improved with it. Nothing like the instant feedback to say that this photo failed completely to make you try again, and start researching what you can do to stop that from happening in the future. I do spend more time editing though, since as I've gained skills in doing it, I find that I can do more. It's kind of like everything else with computers - the great labor saving device lets you do things much faster - only since you can do it twice as fast you now have to do three times more ;^)