In CMS 6 R2 we use the built-in property linklist (swe:länklista). Here you can add links to external sites. When we enter the url www.tänkom.se and publishes the page the ä in the url i rewritten (diferently in different browsers). This causes the link to malfunction.
Will åäö and other international characters be supported in the future?
I just tried this in a R2 site and it works for me. The problem is most likely in the way your templates are coded.