Shaddows - 9:34 am on Jul 31, 2009 (gmt 0)

That means if I own 100 domains and think that Domain #101 fits in

If GOOGLE thinks it fits, analysis of similar situations suggests you should be fine, but there are caveats.

First amongst them is that each of those sites should enjoy a independant backlink profile, and that Site101 should have links other than from Sites(1-100). Homogenous backlinks look spammy.

Otherwise, if its done above board, you are unlikely to get penalised. The links probably will have less pop than other links, but actual penalties are unlikely.

A "penalty-like occurance" may be evident down the line. That's because the links will likely be fully counted to start with, then the association discovered, links devalued, ranking lowered. Not a penalty- your site is higher than if the links were never there, but lower than if the links were independant. Removing the links hurts the site further. I suspect this phenomena is behind the vast majority of "my site just got penalised" stories we get.

Disclaimer: The above is speculation. It fits with my experience, though I appreciate it is not SEO Orthodoxy. YMMV. Forum advice is no substitute for personal experience.

If in doubt, test