it can be possible .. i have also seen an example which showing almost 10 results in first 20 of google of same company with different sites.. but all the hard work has already been done to all those sites to acheive those rankings..
Right now Im dominating a very lucrative keyword with 2 different sites simultaneously at the top of the results of Google. Even though the search traffic isn't high the keyword is very good paying. Most of the time it isn't worth trying to do this, but there are cases where a low competitive keyword is worth doing it multiple times over. Its all trial and error, usually found by accident. It would be very very tough to do with competitive keywords and your competitors might catch on. Its extremely hard to do with just one site let alone 10 on a competitive keyworld.
It's difficult to do for keywords like 'real estate' or 'lawer' but it's easier to do it for keywords like " humuhumunukunukuapua'a"(state fish of hawii)
I agree with the above posters that it could be done for noncompetitive words but you are probably only going to get 3 or 4 sites/pages in the top 10 if it is a somewhat competitive keyword. Google's interest in providing a diverse set of search results and the tendency for sites to float in and out of the top 10 would make it hard to do.
it doesn't matter if ur ip is the same. I have tried this but the content was worded different and they both rank on the first page but the one with the keyword in the URL is ranked 2 positions hire. But they fluctuate I say try it