I have a website that's about a year old and want to start a second site now. To make things easy, I'd host it on the same server. Now I'd also make at least one link from the old site to the new site. Since they're on the same server, will this: - not matter to Google, normal link juice would flow - bother Google a bit, link juice flows but less - piss off Google, some kind of penalty will apply
2 things to consider. Are they on the same IP addresss, or even the same c-block? Are the domains registered with the same registrar information? If the answer to either of these questions is yes, then it would be very easy for Google to tell that you are interlinking. And since interlinking is against Google's webmaster guidelines, my recommendation is not to do it.
Never had a problem with it, it's pretty much the only linking I ever do. Same registrar same IP same host etc and all pages on page 1 as SERPS for the search terms I have targeted. I hear say it is supposed to be regarded as a Grey Hat thing but it has never done any of my sites any harm.