i just found this on versiontracker - it's called
password wallet and it's a mac-based application to save your passwords, and then it can export a file to your iphone that you can view in safari. it is also password-protected on your iphone (using the same password you use on the application on your mac).
i haven't purchased it yet - just checking it out to see how it works. but i thought i'd mention it here since i know that some folks have been looking for a password keeper application, and this one works without hacking your iphone and it doesn't leave an open file on your iphone that just anyone can access...