Now that the 3.1 update has hit iTunes many will jump to download and install as soon as possible, however as the past has shown this is a bad idea if you are a jailbreaker or unlocker.
The 3.1 update includes an update to the modem software that removes over 50% of the commands. The less complex the software is, the less likely it is to find a hole to unlock it with.
What does this mean for you?
If you are using ultrasn0w or purplera1n for your unlock, updating your phone to 3.1 could permanently lock your phone back to its provider's network. There is no downgrading, there is no undoing the 3.1 install, so proceed with caution.
As with every update, wait until the dev team (http://blog.iphone-dev.org) has released the tools to safely install without updating the modem software. This will ensure that your phone remains unlockable, and that at the time you update, a jailbreak is available for you.
You have been warned
