Even hosting them on different servers would not be enough if all the domains are registered under the same name, because Google has access to all the WHOIS info, and sooner or later they'll find the network and then you'll have a big mess on your hands.
If you are doing the linking just for traffic then use a 'nofollow' tag so that Google knows you are not trying to manipulate their algo.
Make sure that this is not a closed network and you'll be fine. Also if most of them are linkfarms that simply point to different pages of "value sites" then if live editor visits you can get and probably will get in trouble. Get plenty of links from out of network sites.
Of course not having all of your sites on one server would help.
If they are unrelated, you probably shouldn't be interlinking them anyway. If there is traffic value for the links, add the no-follow tag. If you have no good reason to link them together, don't. I guess all this was said above. Just thought I'd throw my 2 pennies in too.