Kinda silly to have a "remember me" check box that forgets me by the next time I visit the site. ;)
This has been a bit annoying for me too, although technically the "remember me" applies to the username, not the password. The cookie does appear to keep the username indefinitely, but the password token expires after one day.
This may be hard-coded into the current forum module, but Joe has expressed plans to migrate the entire site to Joomla soon, so there may be more flexibility (possibly even a user-configurable option) in the future.