Windows/Linux, MacOS X with keychain disabled:

+------------------------------------------------+
| Passwords                                      |
|  
| Firefox can remembers passwords so that you do |
| not need to re-enter your login details every  |
| time you visit a page.                         |
|                                                |
| [x] Remember passwords     ( View Passwords )  |
|                                                |
| Master Password blurb                          |
|                                                |
|     ( Set Master Password... )                 |
|     ( Reset Master Password )                  |
|                                                |
|     Firefox will ask for the Master Password:  |
|     (*) The first time it is needed            |
|     ( ) Every time it is needed                |
|     ( ) If it has not been used for [   5 ]    |
|         minutes or longer.                     |
|                                                |
+------------------------------------------------+

MacOS X with keychain enabled:

+------------------------------------------------+
| Passwords                                      |
|  
| Firefox can remembers passwords so that you do |
| not need to re-enter your login details every  |
| time you visit a page.                         |
|                                                |
| [x] Remember passwords     ( View Passwords )  |
|                                                |
| Passwords are stored in your Keychain.         |
|                                                |
|  ( Open Keychain Access )                      |
|                                                |
+------------------------------------------------+