The medium of art is not nearly as the important as the fundamentals of creating the illusion of volume, either with lines, or tonality. Any medium that can give you a gradient within a set hue, or a full spectrum of colors and the ability to paint at a super high resolution, can be used to mimic traditional mediums. Hell.... a computer monitor is only a 'canvas' with hundreds of thousands of tiny points of color, that change rapidly.
The first picture looks like a pencil sketch, brought to the pc and done over digitally, using different layers/modes to retain the initial sketch, while using a smudgy brush to give some shading/tone. It's hard to say.. the wash definately looks digital to me, as I dont see any real brush strokes, but do see alot of 'smudged' areas that don't really feel like true watercolor. Hard to tell with such a low res pic.
If you really want to be impressed with digital painting, check this s**t out
www.goodbrush.com
This guy both blends the lines between digital and traditional painting, and gives digital it's own unique voice. Truly inspiring stuff!