Log in to maemo.org, locate your Annoying Floaty Bar and select Page, find 'edit account' or something like that (and I think alternatively http://maemo.org/profile/edit should work).Scroll down to talk.maemo.org url and enter the url you can find if you hover over your login name in a talk.maemo.org page (should be something like http://talk.maemo.org/member.php?u=<some-number>)

Your accounts are now linked.