I bought an iPhone 4 recently. I've been using Find my iPhone but I find it a little limited.
First, you need to have Wi-Fi or 3G to be able to deactivate or send a message. That consumes a lot of battery. Second, if you have only 3G enabled (which seems to be a more viable solution), the accuracy isn't that good. I've done some tests and it has detected my phone 100m away from where I am. And finally, if none of those are on, you can't lock your phone with a password, otherwise whoever has it won't be able to turn Wi-Fi or 3G on.
A friend who uses Android told me about LostPhone, which is capable of doing all the lock and alert functions by SMS too. I dug a bit and found FoneHome and TapTrace, but none of them seem to be SMS capable.
Does anyone know a solution to this?