I think not.
The parent site should be listed more prominently on the footer and maybe only leave the link to api (if the api will work on this site) and area51.
As the topics become more and more unrelated, simple footer links seem a bit pointless. Right now I guess a lot of us are coming from SO, but down the line each new site should have its own distinct set to users too who may not know (or want to know) anything about programming, etc.
I think it's nice to know that we are part of a larger "family". But I don't really like how the real sites (like stackoverflow and serverfault) are mixed in with all the stuff surrounding them (like api and careers). So I guess I would prefer a redesign of the whole footer.
I'm looking forward to 'migrate to stackoverflow' as a close reason for someone asking for instructions for their (ahem) food processor.