The browser password manager 1Passwd has just been updated to version 2.5b and adds an interesting new feature: iPhone export. You're now able to export your secure passwords and notes to the iPhone from your Mac. The clever thing is that they accomplish this without hacking the iPhone in any way.
Basically what it does is create a special Safari secured bookmarket from your 1Passwrd data "using 448 bit Blowfish encryption." This special bookmarklet is then synced to the iPhone in the normal way through iTunes. When you access the bookmarklet in mobile Safari on the iPhone it prompts you for your password and then gives you access to your passwords, secure notes, etc. Since it's just a bookmarklet in mobile Safari this should not be affected by any future firmware changes, etc.
The latest 1passwd beta can be downloaded from the Agile Web Solutions Forum.