MultiPass doesn't cut it completely but it's a great way to have multiple passcodes for your iPhone. And judging by the state of iOS 7 right now, there's not going to be any multiple-password / guest-mode feature in the iOS ecosystem any time soon.
If you want to get multiple passcodes – as much as five – for your iPhone, MultiPass seems to be the way. Here's more about the new Cydia tweak.
MultiPass lets you configure/setup five passcodes. Five extra passcodes that can be used to unlock the device. So far, multiple passcodes have been impossible in iOS. This tweak breaks that limitation.
Once you install MultiPass, you can configure the new passcodes from Settings → MultiPass. A kill-switch/toggle lets you enable or disable the tweak without having to respring. Setting the passwords is just as easy as filling out text-fields. Once done, press the home button and the passcodes are set.
Of course, the primary criteria is that you should have passcode lock enabled (Settings → General → Passcode) in order to enable and use the tweak.
Why multiple passcodes?
Why do we need multiple passcodes, by the way? This is where justifying MultiPass becomes a little hard. Even though it provides you a way to have multiple passcodes, it doesn't really work like a guest-mode feature.
So from MultiPass's point-of-view, one can say that it helps you when you forget your primary passcode. You can have a simple passcode set as an alternative (1234, for instance). In case you forget the primary passcode, you can use the alternative one to unlock the device.
A multiple passcode feature also makes this use-case possible: you can set a temporary passcode and give it to your friend so they can use the iPhone without knowing your real passcode. Once they've used the iPhone, you can then delete the temporary passcode in MultiPass.
A stronger implementation of this would be the guest-mode or partial-access mode which would need more work. Remember that MultiPass is a free tweak and does a pretty good job nevertheless.
If your requirements are met by MultiPass's feature for multiple passcodes in iOS 7, don't forget to install and try it.
MultiPass is on BigBoss and is free.