I’ve just upgraded [the Operating System of] both my units to v2.0.1; here are some things keep in mind.

Upgrade or not?

If you “update” via a pwned ipsw sure, but if not (meaning you plan to use the legit Apple upgrade) here’s what’s in store for you; quoted from the DevTeam (rephrased, since to reflect the release of the tool)

If you own a first generation (2G iPhone), you don’t have to worry, PwnageTool will get you where you want even if it you prematurely updated. 2G is completely pwned at every conceivable level and you’ll always be OK. But if you own a 3G iPhone and are looking for unlock in the near future, don’t use Apple’s update.

If your 3G iPhone is on a regular contract and you always plan to be with the carrier then you can update but you will lose the jailbreak and access to third party (non AppStore) applications.

If your 3G iPhone is not on a regular contract and you plan to use it on an alternative network to the carrier that supplied it then do not update unless you do it with the new PwnageTool.

For other points discussed below, I’m assuming a jailbroken scenario.

Before everything else

There are three terms to consider when dealing with iPhones:

1. Activating – the process of getting your iPhone past the state of only being able to dial emergency numbers. An iPhone is usually activated online after verifying a legitimate cell plan/account.
2. Jailbreaking – the process of “freeing” your iPhone; allowing read/write access that was once reserved exclusively to iTunes. This is integral because normally, iTunes alone gets to mess with your phone (adding apps, etc.)
3. Unlocking is allowing the iPhone to be used with any mobile carrier.

I thought I’d say this because regular people tend to assume either 2 and 3 are the same thing, or assume that once 2 is achieved, 3 would come naturally, it doesn’t work that way.

Unlock?

2G phones are covered. 3G phones on the other hand, still only go as far as getting jailbroken.

Restore a backup or start from scratch?

Restoring settings from a backup is safe; you will retain all your AppStore applications and data, yay!

Even the “cracked” IPAs floating around will still restore with data and all intact – woohoo! ;)

You will have to reinstall the jailbroken apps though, unless you preinstall them on the ipsw

MobileSafari problems

In case MobileSafari acts up (e.g. doesn’t remember cookies); symptoms of this is if you can’t remain logged in on some accounts. Fix the directory cookie permissions via SSH. In Terminal, login to your iPhone and type:

chown mobile /var/mobile/Library/Cookies/ chown mobile /var/mobile/Library/Cookies/Cookies.plist

You can also do it this way:

chmod 777 /var/mobile/Library/Cookies chmod 666 /var/mobile/Library/Cookies/Cookies.plist

The first method is preferred as it sticks to the “Apple Standard” of file permissions; unlike the latter, which uses an “allow all” hack/approach – which I guess by nature is less secure.

You can also save yourself the headache by installing BossPrefs from Cydia and use its “Fix User Dir Permissions” option.

iPod touch users are safe since the issue mentioned in the start has something to do with the 3G baseband – which doesn’t exist in the Touches.