You can.
We will be waiting.
Could somebody write how to connect iPhone 3gs via Bluetooth or USB?
You can.
We will be waiting.
Can be done via wireless, i know thats not exactly what you asked for, but its one option. I'll have a go over usb and bluetooth and let you know if I get anywhere. Meanwhile this might help:
Firstly, jailbreak your iPhone and install MobileTerminal and SOCKS Relay (both of which can be found through Cydia).
On your BT machine setup an ad-hoc network.
This only seems to work (for me) using a B-class network.
Connect your iPhone to the network and make a note of your phone's ip address. At this point, if your phone's 3g symbol turns to a wifi symbol, open safari and refresh the page; doing this should revert the phone to the 3g symbol, without dropping your phone's connection to the ad-hoc network.
At this point the tether should be complete.
NB. As this is a socks proxy, your BT machine will only be able to use the phone's 3g internet connection through software that can be configured to use a socks proxy.
On your BT machine, open Firefox and, in the address bar, type: about:config.
This will take you into firefox's settings. In the filter bar type: Socks
Set the network.proxy.socks value to the phone's IP address.
Set the proxy_port to: 1080
Set the socks_remote_dns boolean value to: true
Finally in Firefox, goto: Edit > Preferences > Advanced > Network > Settings...
Select Manual proxy configuration
Click OK
You should now be able to browse on your BT machine using your phone's 3g internet connection.
PS. If you install Openssh on your phone (again via Cydia), you can use this tether to negotiate and manage your phone file system on your BT machine.
Hope this helps.
you may want to google it, I know that for the blackberry there is a tool called thetherry or something like it that you download to your phone and also to your laptop. So I am pretty sure there is something similar for the iphone.
Umm...PdaNet? Assuming it's jailbroken you can tether it via USB or use it as a wireless AP by creating an ad hoc network. Just get it from cydia, it comes with instructions. There are numerous other ways to tether as well. Google. Also, I'm pretty sure this isn't related to BT4 in any way. This is an iphone question.