I’m considering getting an Ipod Touch, with one of the uses being to keep track of account numbers and passwords.
Can a Touch be password protected?
Yes. It’s a four digit number.
To expand upon Leaffan’s anwer, go to Settings > General. Scroll down and there is a place to toggle Passcode Lock on or off. Toggle it on and set a four-digit passcode.
Alpha-numeric, or just numeric?
Numeric. That’s why I said “number.” 
So it’s pretty much unprotected from anyone with 10 or 15 minutes to spare.
I dunno. I guess at worst case you’d need to run through all 10,000 possibilities. If you consider it might typically take half that long then 5,000 X 15 seconds per try still comes out to 20 hours of work.
It might have a lock out feature after so many unsuccessful tries, I’m not sure. I’ve only tried to break into my kids’ a few times!
How do you get 10,000 possibilities out of 4 digits?
Upgraded to iOS4, the passcode on a Touch can be simple (4 digit) or alphanumeric.
0000-9999
If you wanted to try every single possible combination.
Easy, 4 spaces, each space has 10 possible digits, (0-9). That’s 10^4, or 10,000.
Me am not math major. Me am sorry.
10 x 10 x 10 x 10 = 10,000.
My wife’s got it enabled on her iPhone and if you get it wrong three times it locks you out for, IIRC, two minutes.
Also, there’s a digital wallet app that you could keep the stuff in. I don’t use it myself but it has an alphanumeric password system and was at least 10 digits long.
–Cliffy
I would recommend using a little extra protection if you’re keeping account numbers and passwords. 1Password for iPod Touch is one of the popular solutions.
Thank for these. It sounds like the base level protection isn’t up to the level I’d want. These might do the trick.
You can also set it so that if you get the wrong password 10 times in a row it erases all data (simple checkbox when activiating password).
I’m not familiar with specific solutions for Apple’s products, but just in general you probably want one that actually encrypts the data on the device, rather than just relying on the operating system’s password to restrict access.
On my (old) Palm OS phone I use Ilium Software’s eWallet; I’m sure there are many to choose from for your platform, as well.
What exactly is your concern? Are you surrounded by people who will try repeatedly to access your Iphone content so doggedly that they might spend hours or days trying to get through?
The one I mentioned in my post does (1Password).
Those small portable devices are easy to lose, forget, or steal. In my case, I have long random passwords for things like my online bank account, so I need to store those in a file somewhere. I am willing to go to the extra trouble to store them in an encrypted file.
It seems to me that an Ipod/Iphone is a very bad place to store passwords, but I’m interested in hearing the possibilities. What format would I save special files in? How could they be hidden? How could they be encrypted?