It isn’t 4.1, but Apple has released an update for all of its iDevices out there. 4.0.1 is available for the iPhone and iPod touch, while 3.2.1 is here for  all iPads.

 The only change noted so far is the signal bar heights, shown here:



If you see any changes? Respond in the comments.

Update 1:A report has sprouted that 3.2.1 kills the Spirit exploit. iOS 4.0.1 patches the ultrasnow. Basically, as always, jailbreakers should wait until the Dev Team gives the green light on the update.
 
Update 2: We have reports that it isn’t available for iPod touch users, at least not yet.

Update 3: It appears iOS 4.0.1 does not change the baseband, and can be jailbroken with the latest redsn0w. Only MB model devices can be jailbroken.