What can/am I able to jailbreak and unlock for 3G (windows)?

[tbm248]

I have a 3G and am jailbroken on 3.0 (or 3.0.1, definitely before the 3.1 update).
I have a windows computer.

Can I jailbreak to the new software (3.1.2)? How so? How about unlock? I am only interested in the unlock (or ability to unlock) for resale value, but I've read various threads that jailbreaking on 3.1.2 makes it impossible to later unlock. I want to be very careful with that since again, if/when I sell my phone, I want to unlock it and raise the value.

Also, what are some of the downsides to jailbreaking to the new software?

[Tokiopop]

Okay, stay on 3.0.X and DO NOT update through iTunes. Use Redsn0w (http://thebigboss.org/hostedfiles/redsn0w-win_0.8.zip) to Jailabreak (that's a windows version). Now follow this (http://www.iclarified.com/entry/index.php?enid=4301) tutorial (you can skip to step 3) and you'll be Jailbroken.

If you wanted to update to 3.1.X and still be unlocked, you would need a Mac or someone with a Mac to use PwnageTool to create a custom IPSW that does not contain a baseband update. If you could get a hold of one of those all you need to do is hold shift and click restore in iTunes, select the custom IPSW and restore to it. But make sure if someone gives you a custom IPSW it does NOT update the baseband.

Now to unlock, just follow this (http://www.iclarified.com/entry/index.php?enid=4253) and you're done!

There are no downsides to jailbreaking. Some complain of shorter battery life and slowdown, but that depends on what you install. If you don't install anything, you'll be fine.

[Moi un Mouton]

The breaking news on this subject is that Geohot plans to release an unlock for the new baseband on 4th November.

There's an active thread about that running on the forum already, and you can read more here:
http://iphonejtag.blogspot.com/2009/11/information-campaign.html

Help spread the word that no-one should pay for the unlock via sites that steal Geohot and the Dev Team's work - it's free