UPDATED 08-11-2009 18:42 PM EST
If you have recently updated to the latest version of Safari and your 1Password icon is no longer appearing, you will need to update to the latest version of 1Password to restore the icon in Safari.
1. Upgrade 1Password
Normally all you need to do is update to the latest version of 1Password to restore the Safari integration. Load 1Password, click on the 1Password menu at the top left, and select Check for Updates as shown here:

After upgrading, restart Safari and the 1P icon should return.
2. Snow Leopard Users
In 1Password 3, full support for 64-bit Safari is available. When using 1Password 2, Snow Leopard users need to configure Safari to run in 32-bit mode.
To do this, use Finder to locate Safari and then ctrl-click on it and select Get Info. Enable the Open in 32-bit mode checkbox as shown here:

Note that the Open using Rosetta checkbox must not be checked. After doing this, restart Safari.
3. Customize Safari's Toolbar
If the icon does not appear, sometimes the 1Password icon cannot be automatically to the toolbar. Try ctrl-clicking on the Safari toolbar and select Customize Toolbar...; this will bring up this window:

If you see the 1Password icon there then just drag it to your Safari toolbar. If not, proceed to the next step.
4. Verify 1Password browser extension is enabled
Load the main 1Password application, go to the preferences, select the Browsers tab as shown here:

It needs to be checked (i.e. have a checkmark in the box next to Safari)
If it is already checked, then toggle it (uncheck the box and then place a check in it again) and restart Safari.
Still no icon? Proceed to next step.
5. Reinstall the InputManager
Click on the Gear icon on the Browsers tab and select Remove Input Manager as shown here:

After removing, select the Gear icon again and select Install Input Manager.
Restart Safari and you should now have a 1Password icon in Safari.
6. Other Plugins
Sometimes 1Password is able to load fine, but the icon never appears in the toolbar or in the Customize Toolbar window. If you are missing the icon but are able to use the CMD-\ restore login keyboard shortcut, then 1Password has loaded fine and the problem is likely a conflict with another extension. For example:
- There is a known conflict with EverNote, and we posted a potential solution to keep 1Password's button in Safari 4's toolbar that we found on the EverNote GetSatisfaction page.
- There is also a known conflict with Saft where the very first window created will not have the 1P icon, but subsequent windows will have the icon.
If you are experiencing this issue, as a test, try removing the other plugins and see if the behaviour changes. Alternatively, you can decide not to use the 1P icon at all and use the "key" in the Main Menu instead. You can access all of the 1Password features from the Main Menu by going to the 1Password > Preferences > Browsers window, and enabling the Display in Main Menu option in the Advanced menu (i.e. under the "gear").
7. Snow Leopard Users and Folder Permissions
On Snow Leopard, 1Password 2 needs to update this file:
Code:
/Applications/1Password.app/Contents/Resources/SupportedBrowsers.plist
Normally 1Password will update this file for you automatically, but your user account must have the required permissions to edit it. If you do not have permissions, you can fix this as follows:
- Use Finder to navigate to /Applications/1Password.app
- Right-click 1Password.app and choose "Show Package Contents," then browse to the Contents folder.
- Ctrl-click on the Resources folder and select Get Info.
- In the Info window, at the very bottom, you will see a Sharing & Permissions section. Add yourself as a user who is allowed to read and write the file by clicking the + button and then double clicking on your name. At this point OS X should prompt you for your admin password.
- Open the Resources folder and ctrl-click on SupportedBrowsers.plist and select Get Info.
- Give yourself read and write permissions to SupportBrowsers.plist using the same process described in step #4.
Now that you have write permissions to the SupportedBrowsers.plist file, you can now restart 1Password and it will automatically update the file for you. You can now restart Safari and the 1P icon should return.
If the icon is still missing, open /Applications/1Password.app/Contents/Resources/SupportedBrowsers.plist and search for Safari. The MaxBundleVersion should say 6532. For example, this is the relevant part of the file with the new version number:
Code:
<key>com.apple.Safari</key>
<dict>
<key>ClassName</key>
<string>OPWebKitPlugin</string>
<key>MaxBundleVersion</key>
<string>6532.0</string>
If it is not 6532, edit it and save the file. If the file cannot be saved, double check the permissions of the file and the Resources folder.