The Dawn space probe that entered orbit around Main Belt asteroid 4 Vesta on July 16 has been returning steadily more detailed photos. The Dawn mission will linger at Vesta for the next year, and then leave it for another Main Belt asteroid and the largest object in the Belt - Ceres, where it will arrive in 2015. Dawn will be the first probe ever to enter orbit around one non-Earth object and then leave for another.
First, for a little perspective, here is an image of 4 Vesta as seen from the Hubble Space Telescope, which is in orbit around Earth:
The above image has the benefit of being in color, which the Dawn probe has not yet taken - but we can get a sense of the colors of the asteroid we can expect to see by the HST photo. The orange-ish / brownish tint is expected for objects much beyond Mars, as that is a typical color of some types of ices that boil off closer to the Sun. HST images of Ceres have a similar coloration, and Ceres and Vesta together are respectively the 1st and 2nd largest objects in the Main Belt.
Here is the orbital path taken by the Dawn probe, and its future journey once it leaves Vesta, just to get a sense of where the asteroid is located:
Now, here is a Dawn image taken June 14 (none released so far are in color):
June 24:
July 9:
July 17:
July 18:
Here is a great size comparison of Vesta with some other significant asteroids (it's highly detailed at higher resolution, so you may wish to click on it and look at larger sizes):
And also a comparison with Ceres and the Moon, both of which are larger than it:
Now, Vesta's surface gravity is about 0.04g - meaning that if you weigh 200 pounds on Earth, you would weigh 8 pounds on Vesta at a mean distance from its gravitational center of mass. It isn't quite spherical, so there would be significant deviations, but that is roughly the number. You may, however, note the sort of fluidly-wrinkled texture in the July 18 image, indicating molten resurfacing at some point - something considered unusual in an asteroid, as it tends to be easier for them to simply shatter and fly apart in an impact than heat to the point of molten flow while remaining cohesive.
While there is no immediate economic significance to exploration of Vesta, over the long term I think it will prove an important waystation for exploration and development of both the Main Belt asteroids in general and the outer solar system. It and Ceres are, I would guess, quite likely to develop some level of human habitation over the next three to four centuries due to this prime location and their relative massiveness (providing not only a small measure of gravity, but also accumulating ices), but I won't bore anyone by speaking further on that - I realize it's disconcerting to most people to think on such timescales.