If you read this blog (or any other iPhone-related blog) on a regular basis, you know by now that you shouldn’t update your iPhone if you rely on a jailbreak/unlock, at least until a jailbreak and unlocking method has been found. The problem is there are lots of new jailbreakers that are not aware of the risks associated with updating.
Assuming you have your SHSH blobs on file, you will always be able to downgrade your iPhone iOS to a previous version, however you will not be able to downgrade your baseband, which is key to unlocking the device. If you rely on an iPhone unlock and update your device, you might lose the ability to unlock forever.
While no iOS 4.1 jailbreak has been found yet, I’m sure the Dev Team is working hard on it. For up-to-date information about these topics, I suggest you regularly check our jailbreak section and our unlock page.