If someone has 5 totaly different(non duplicate) websites with unique URLS, all indexed, all pageranked but has the same IP for all of them and points links to a website of mine. One link from each site. Is this ok or not? Will google care?
I think the big issue here is percentages. If the ONLY links you have are coming from the same IP, that is probably a red flag and will get all the links beyond the first one that the engines recognize disregarded. The best course of action is to leave those links in place and work on getting lots of others that are not from the same IP or even the same Class C. Remember that the engines look for natural links, which means (among other things), a random dispersion of IBL IP locations. Anything that looks manipulated (unnatural) will probably raise some flags. That doesn't mean a link can hurt your site... just that it may be worthless if it's deemed unnatural.
I do not believe in any theory about red flag or negative points etc... I know one webmaster that host 5 different sites but with same thema, have links between sites and score excellent on all search engine. All his sites have same ip address and by most searched words (according overture) his sites comes always in first 10. Believe or not but it is true.