IS (also named VR, OS, VC) in body has the advantage that it works for all lenses, even old manual lenses. You buy this piece of technology only once when you get the body. For upgrading the IS (e.g. additional features) you need to get a newer camera body. Also, the effect is not visible in the viewfinder, the stabilizer only works in the moment when you take the picture. If there are third party lenses that come with integrated IS one of the stabilizing systems must be switched off: either in lens or in body.
IS in lens is something you buy with each lens which comes with IS and pushes the price a bit upwards. The IS can be made very specifically for this lens, depending on focal length and lens construction. Newer versions of a lens might get an updated version of IS. If the manufacturer does not equip a certain lens with IS then there's no way to get it. The effect is visible in the viewfinder once you press the shutter half for focusing. This might result in a bit more battery drain if you focus several times.
IS is useful for longer focal length (e.g. 85mm and above. Normal lenses and wide angle don't really need IS. Proper handholding technique is enough and should be trained in the beginning.
Dont need to use what your friends are using. Just buy that suits your budget and move on from there.
The other thing about sharing lens and accessories, who shares them regularly anyway?
D3s / D3x / 18-55 f3.5 - 5.6 / 55-200 f3.5-5.6 / 50 f1.8