Canon 24-105mm f/4 L IS USM
One of the newest Canon L lens released, the 24-105mm f/4 represents convenience without compromise. The lens has the benefit of an incredibly versatile focal length, along with latest generation image stabiliser, which makes it the ultimate walkabout lens where image quality is concerned.A few random photos (from gallery 'Canon G2 Gallery' taken with this lens (click thumbs for bigger versions):
It does give away one stop of light when compared to the 24-70mm f/2.8 Canon lens, but with a sharp f/4 and IS the difference is closer than it might appear.
Both the 24-70mm f/2.8 and 24-105mm f/4 have their separate intended uses, but in terms of a general walkabout lens the 24-105mm cannot be beaten.