> I was surprised to discover that
> 
> >>> import datetime
> >>> x = datetime.date(2004, 9, 14)
> >>> y = datetime.datetime(2004, 9, 14, 6, 43, 15)
> >>> print x == y
> True
> 
> How can these two objects be considered equal?

They should not be.  Please open a bug report.  The 
problem is due to that datetime.datetime is a subclass 
of datetime.date:

>>> isinstance(y, datetime.date) True
>>>

and date's comparison implementation believes that 
instances of date subclasses can be compared as if 
they *were* dates.  Indeed, since a datetime.datetime 
is-a datetime.date, it's a bit hard to see why that 
shouldn't be allowed, and offhand I don't know of a 
principled way to fix this without breaking existing code 
that compares instances of user-defined subclasses of 
datetime.date to instances of datetime.date.

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user_id=31435

Thanks for the report.  Comparing a date to a datetime now 
acts like a mixed-type comparison; user-defined subclasses 
aren't affected; see NEWS for details.

Lib/test/test_datetime.py 1.49
Misc/NEWS 1.1135
Modules/datetimemodule.c 1.75