Rasm, I do not intend to question the sanctity of the theories in that site, however, I know for sure that if you convert a date time value in Excel to its value, the number returned will be equivalent to the number of days starting from 1/1/1900 0:00:00, inclusive of all leap years and leap seconds.

So based on my theory, 10/27/2011 12:01:51 AM will be converted to 40843.00128 (days) which means 40843.00128*3600*24 seconds = 3528835311 seconds

Now, if you reverse this to date, using a simple text function like so =TEXT(D1,"m/d/yyyy h:mm:ss AM/PM"), you would get the original date 10/27/2011 12:01:51 AM

If you are still confused, I can prove it with an attachment