two cases:

1) page-a of site-1 to page-a of site-b, page-b of site-b to page-b of site-a
2)one direction but in a circle: site-1 to site-2 to site-3 to site-1

do you think they are one-way link for PR?

AFAIK (1) is probably seen as reciprocal linking, while (2) probably isn't -- yet. I read somewhere that search engines are expected to be able to recognize that type of linking in the future. I don't know if the future has arrived yet. :)

OTOH, whether or not reciprocal links carry less weight than one-way links do is a debate in itself.

Lois

thanks.
if so, we should not do anything about site-exchange or link-exchange.

there are too many things to know for PR.

option 2 that you mentioned is a very good and strong link strategy as it is indicated as being not a link reciprical link method... however as wrotespeak says the day might have come, however im sure option 2 makes a strong link method!