how secure is 3g/tethering?
 

I was just curious about something. I use my phone to get internet on my laptop via bluetooth. How secure is this? Can people sniff this traffic?

I suggest picking a long passcode for the bluetooth connection. If you use 1234 or 0000 then you could theoretically be snooped on. It would take them quite some effort, but it wouldn't be impossible.

If the traffic is really important, then consider a VPN service or using wired tethering.

If there is something that you want to be secure, make that happen at the protocol level, either through SSL or VPN or something similar. Once it gets past the local hardware you have no control over the security of the transmission, so even if the laptop<->phone connection is 'secure' (or tethered) the phone<->tower connection won't necessarily be, or the next hop, etc.