http://support.apple.com/kb/HT3574 for availability options.
As far as wireless tethering goes, the only way I know of doing it is to create an adhoc network between your device and your PC/Mac, then bridge the connections.
Note the following.
Ethernet sharing is supported on virtually all modern devices. If receiving ethernet on one and you want to wireless to [one] other use ADHOC. Note the following for Adhoc on windows. Terminating the connection terminates the ICS - Internet sharing connection - meaning you have to manually restart the service and connection., or reboot, before you can connect again. This applies to both devices.
2nd option is to create a wireless network. Give it a name SSID and a password which should be of at least WPA or WPA2 (ipad required) strength.
Bridge your Ethernet to PC with your outgoing wireless network. There are security considerations in making a bridge in this fashion.
1) Make your Ethernet side of it a Public network (change from private) or work) Note tha on windows machines you cannot make a bridge if one of the connections is a managed network - see your systemnetwork help for details.
2) Ensure your firewall is on and only allowing traffic for the required ports required for apple/itunese/mail/etc See apple support for details or consult the Internet Port Authority [IANA] which has virtually a full listing.
3) If your firewall gives you the ability to set machine connection restrictions then use them - windows firewall on Vista and win7 support this, http://technet.microsoft.com/en-us/library/cc875811.aspx gives full details on setting up. Third party firewalls will have similar ways to achieve the same.
4) Check available services to be shared on your network, internet is shared by default with ICS turned on, and the Windows Firewall service needs to be running, even if the Firewall itself is Off (as in using a third party program such as Norton, Avira, Kaspersky, etc)
Each of these will give you options on how to set port or machine ID sharing options. Make sure you use them since bridge networks with an internet connection are basically open networks, even if you need to establish the network connection to start with. The internet side of the connection is an open network.
5) Make sure all security updates are in place and up to date, and minimise file share and public folder exposure if using this technique.
Regards. Ct
