We have done a bad job explaining 1Password 2, 1Password 3, and Snow Leopard and inadvertantly created a lot of confusion. I'm sorry about that and hope that this post will clear things up.
1Password 2 on Snow Leopard
1Password 2 works fine on Snow Leopard "out of the box". The main application and all browsers work fine, except Safari. Safari is special because starting in Snow Leopard it runs in 64-bit mode which is very different than Leopard or Tiger.
While 1Password 2 cannot run in 64-bit Safari, it is possible to make it work in 32-bit mode. We just published version 2.9.29 to make it easier so all you need to do is highlight Safari in Finder, ctrl-click on it and select Get Info, and enable the "Open in 32-bit mode" checkbox under the General section.
Once 32-bit mode is enabled, restart Safari and the 1P icon should appear in your toolbar. If it doesn't, please see this troubleshooting guide for help.
To recap, you do not have to modify anything to get 1Password 2 working on Snow Leopard if you decide to use a browser other than Safari. If you want to use Safari, you need to configure it to run in 32-bit mode.
If 1Password 2 gives you an error that it cannot launch on Snow Leopard, you need to update to the latest version of 1Password 2. Simply download the latest version from our website and be sure to drag your existing copy to the Trash before copying over the new version.
The upcoming 1Password 3 is able to run in Safari even in 64-bit mode, and you can participate in the beta if you like. Read on for details.
1Password 3 Beta
1Password 3 is the largest upgrade in Agile's history. It contains many new features and has been in development for over a year.
We were hoping to finish 1Password 3 before Snow Leopard was released so everyone could enjoy the 64-bit Safari goodness, but we didn't make it. To compensate, we decided to open up the beta testing to all Snow Leopard users.
1Password 3 has been in private beta testing for a long time now and has proven to be quite stable. However, if testing software and reporting issues is not your idea of fun, we recommend that you wait for the final 1Password 3 release later this year. In the meantime, you can continue to use 1Password 2.
If you want to join the 1Password 3 Early Access team, all you need to do is start 1Password 2 on your Snow Leopard installation. When you do, you will get this prompt:
Simply click Get 1Password 3 and you will be taken to the setup instructions. If you do not see this prompt, update to the latest version of 1Password 2 by following the instructions in the 1Password 2 on Snow Leopard section.
I'm sorry for any confusion that the earlier posts may have caused.
Co-author of 1Password