As of current I got 5 websites hosted on a single IP. I know there's nothing wrong with this initially (I don't interlink them). The thing is; 2 of the sites are optimized through blog networks exclusively which means they will most likely get penalized sometime in the future. My concern now is if these penalities will affect my other sites. Note that all my 5 sites are about the very same niche - in in general quite similar.