A thread at Search Engine Watch forums named Fear of spamming depicts the story of a Webmaster who is afraid to link four web sites together. Let me quote the Webmaster's exact words:
We have four websites in the legal field. One is a larger umberella site for the law firm and its two main practice areas which are criminal defense and injury law. The second is taylored specifically to DUI defense.. The other two sites are blogs with articles on DUIs and the other on personal injuries in our state. Our concern is that we don't want to be prcived as spamming the SEs. There is no duplicate content and no interlinking between any of the sites. What issues should we look out for to steer clear of being banned. Thanks for any input. Please excuse me if I placed this post inappropriately.
What hurts me more is the next response, "The only "penalty" you could incur is a penalty if you inter-link those websites. If you must inter-link them, you might consider using the rel=nofollow attribute on your links." Is that true? Well, it is possible. But interlinking four Web sites can rarely get anyone penalized. Plus if they are all related and linked to in a manner that shows it is done for business reasons (i.e. Jupiter, Developer Shed, etc.) then there is nothing wrong with it. Four web sites, I would go on record as saying, no problem. But as Tim Mayer said, it is all about "intent" and since search engine algorithms are so smart to figure out "intent" when it comes to spamming, and since Google doesn't hand remove sites, then you should have no problem interlinking four web sites even with improper "intent". (Sense my sarcasm there)
Look at the fear search engine place in normal Webmaster's eyes. Look what hoops Webmasters need to go through. It is 2005.