This was submitted as part of Ubuntu's "100 papercuts" event.  The Ubuntu people identified the bug as upstream and asked that it be filed here.  The text of the bug is as follows:

When accessing a windows file share (or other network resource) that requires a password, the radiobutton defaults to "Forget password immediately". While this is understandable for security reasons, it is a usability "paper cut" because one will typically be confronted with the same password prompt again in very short order (without even closing the nautilus window). Just yesterday this got a smirk out of a Windows user looking over my shoulder that I had to enter the password "again." This has also been an annoyance for me for quite a few years.

The default should be "Remember password until you logout" which will be more what end users are used to without too great a compromise on security.

To repro:
1. Using nautilus, access a windows file share that requires a domain\username\password. For me this typically happens when I access the root share of a computer (smb://servername) .
2. Enter authentication information, keeping the radio button on "Forget password immediately".
3. Access one of the shares listed. Usually when I start with the root share of the computer, keep the "Forget password immediately" setting, then access one of the listed shares I am prompted for a password a second time.

Repeat the above procedure, but this time select "Remember password until you logout". When you access the share below the root it will not prompt a second time (and my windows-using coworker would not have smirked).

Other information:
With Ubuntu's database this is bug #392589 (https://bugs.launchpad.net/hundredpapercuts/+bug/392589).