I use Ubuntu 11.10 with xfce & gnome, and am dependent on company network infrastructure for windows shares (as well as Outlook, but more on that later). So I also fall under their password policy, which dictates that I change it every so often. I keep up to date with all updates from Ubuntu.
The first time that I mounted network shares (with a bookmarked smb:// URL), I checked the 'Remember forever' option and it worked just fine. Reboot, mount a network share, no problem, all automatic. Then came the first mandated password change and it took all the fun of working with network shares away, because now I have to fill in the domain and the password after each reboot, no matter how often I check the 'Remember forever' box.
I also compiled 'openchange' in the mean time (out of dissatisfaction with Evolution), which includes a 'samba4' sourcetree. Could that have anything to do with it ?