From what I can tell, the pros you see posting on the likes of
www.photo.net do several things.
1) They are just good/talented people. They have an eye. They understand lighting, depth of field, framing, and the limits of their talent and equipment.
2) As soon as they receive a new camera body and lens, they send BOTH back to the manufacturer for precise calibration.
3) They have good equipment but not everyone has the latest DSLR body and bag full of the best lenses. (I have seen awesome shots with a Sony F828 for example.)
4) They maintain their equipment: clean the lenses, clean the sensor, mirror box, etc.
5) They often shoot in RAW format. Other in-camera settings are often neutral.
6) They are Photoshop geniuses and know exactly what they want their result to look like.
Sharpness and clarity are a result of a really good body and lens combination. This means: 1) A clean sensor, 2) A good lens, 3) A clean lens, 4) Factory calibration of both lens and body. Sharpness and clarity also depends on how slow the shutter speed is, whether the lens/body has Image Stabilization, whether you're using a tripod, high ISO settings, etc. Yes, a good Canon "L" usually produces better out-of-camera/non-photoshopped images than a non-L lens, but this is not always the case.
By shooting in RAW format, you have tons of options in Photoshop in terms of correcting contrast, brightness, color, saturation, vignetting, noise, etc.
The Pros also use lots of extras too: 1) External flash for bounce flash/angled flash, 2) Various filters, etc.
There is a lot of work in getting really good shots...again, my definition being a lot what you see on
www.photo.net in the "Top Photos" section.