In view that iOS 5 it is possible to your iPhone without an iPhone with iTunes to sync cable. As long as your iPhone and PC on the network with, iTunes can use this wireless connection to communicate with your iPhone. If you can use the Personal Hotspot feature of your iPhone, it is also possible to do this without a router. For this, your iPhone will not use your mobile data connection.
Using Personal Hotspot mobile data connection you can use your iPhone to your laptop for example the internet. The connection between a computer and iPhone is also used internally: the iPhone and laptop connected, they can be synchronized via the Wi-Fi connection. Therefore you do not need a wireless router to stand between the two devices. Since the devices in the network communicate with each other, nothing is sent via your cellular data connection.
Other apps could communicate with each other using Personal Hotspot. Gear Diary says the video player app AV videos from a MacBook to an iPad can be downloaded from the iPhone through a network set up.
Not everyone with an iPhone can use the Personal Hotspot. This function must be activated by your service provider, something you often have to pay for it.