I certainly wouldnt require anything that is not a final ruled law - and even if it were to ever get ruled on as required - I wouldnt expect to see it on submitted free sites - the law as written says the root of the domain as Alex said - and if you have subdomains they would require it - but not directories (at least right now).
If it wer on a free site it would be checked and the page that it goes to had best not have advertising - as some sponsors have done - as then it would count as a link. It would also have to fulfill the other rules like not opening in a new window etc - But why in the world would you put a traffic leak on a free site? Unless of course you submit free sites built on the root domain
