I'm running Safari 5.1 dev preview on Snow Leopard, and just installed the latest version of 1Password. The old 1Password plugin was working fine even in 5.1 with the second-newest version (3.6.0 or some earlier build of 3.6.1, don't know which), but apparently was removed in favor of a Safari Extension in the newest version.
What I'm missing is the old way of defining a keyboard shortcut. 1Password used to have menu items, which could easily be mapped to arbitrary keyboard shortcuts through System Preferences. This is no longer possible. Now, I've seen it mentioned that Cmd-\ is the way to invoke 1Password. This, however, fails on Finnish and other keyboards where typing "\" requires the use of a modifier key. In my situation, the \ character is typed by pressing Opt-+ (where + is next to the 0 key). Thus, to produce Cmd-\, you'd actually have to press Cmd-Opt-+, which doesn't invoke 1Password. This is probably the case with some other non-US layouts, too.
Either the shortcut needs to become customizable, or it needs to change to something that takes into account non-US keyboards with modifier combos.
This single regression has made 1Password about 80% more laborious for me to use. I practically never used the toolbar button before the new version came out, now I am forced to. This is aggravated by the lack of contextual menu functionality.
The addition of contextual menu items in Safari extensions should be simple enough, as described here: Adding Contextual Menu Items
(Apple developer docs). It would be great to get the old shortcuts (password generator, identity and CC filling, etc.) back.
Is there really *no* way of 1Password working as a proper Safari Plug-In from 5.1 onwards? Like Flash does? Seems that the plug-in way would be a lot more powerful and better integrated into the Safari experience.