Which Google Earth version supports the highest resolution?

Most land areas in google Earth are covered in satellite imagery with a resolution of about 15 meters per pixel and highest resolution is 1 inch per pixel. At the highest resolution of once-inch resolution where each pixel represents one inch (or 2.54 centimeters). It won't appear blurry until you descend below 50 feet or so.

Most of the high-resolution imagery is aerial Photography taken from aircraft flying at 800-1500 feet rather than from satellites.

See KML in related links to see examples of each resolution.