Link farm worry in regards to a site network

Would Google consider this bad?

[Ducain]

I have a small but growing network of websites (all in a certain genre), and I also have a 'central hub' website that serves as the launching point for the sites.

The hub/network site links to all of the smaller sites, and all the smaller sites link back "We are a part of blah network...", but none of the sites link to each other.

Is this ok, or is there a problem with this? If so, any suggestions on how to do it better?

[lammert]

Marking all cross-links with rel="nofollow" should be enough. Currently Google is getting better in detecting this kind of site cross-links and rather devalues them than penalize them as happened in the past.