Classes and modules aren't the same, and this will lead to confusion both when users expect it to act like a module.  It's possible to create a fake module object and populate it, but I don't see a big benefit here to making something that looks just like datetime, with a few changes to the behaviors.  That just leads to confusion for users and readers when the 'utcnow' function doesn't return what the Python docs say it returns.

Better, I think, to just create normal old utility methods.  One would be sufficient (turning a UNIX timestamp into a datetime), but an extra method to return the current time as a datetime is fine, too.